Wednesday, November 27, 2013

Gameweek 13 Preview

Thursday, November 14, 2013

Getting defensive

Attack-minded defenders have long been considered one of the key ingredients to a successful fantasy team, and while I may personally suggest this quest is sometimes overpursued, there's no arguing with the overall premise that such a player can be extremely valuable.

Two issues arise though.

First, managers tend to overvalue this threat, paying huge premiums which simply cannot be justified. The most obvious example of this in recent times has been Leighton Baines (who has rarely justified the huge premium required to get him) though we've seen similar trends in the past with the likes of Thomas Vermaelen, Nemandja Vidic and even Joleon Lescott.

Second, managers tend to overvalue past success, which can be ill advised at the best of times but is particularly dangerous with defenders. With a few notable exceptions, defenders tend to enjoy limited chances to earn points and the sample sizes involved are generally very small. Thus, a player with the odd goal coming from a handful of shots is no more likely to score again than any number of comparative players who haven't yet registered a goal this season. Of course, we're not saying those "unlucky" few are any more likely either, but the latter are almost certainly held by fewer managers and probably come with a lower price and thus deserve our attention.

The chart below can be sorted by team and plots a player's price against his expected points purely from attacking means (xP). We're trying to identify players whose production exceeds or matches those available in his price bracket and this is best done on a team by team basis (as otherwise you are trying to compare too many variables at once). Once you identify the 'best' options from each team, you can then move on to comparing them all considering other factors.


A note on expected points. In the model, two bonus points are awarded for each goal, based on a approximate study of how these are generally handed out. Hence, if a player has racked up enough shots to score exactly one goal, his xP would be eight rather than the six you might expect.

Arsenal
Sagna and Mertesacker have produced the same attacking points to date with the Frenchman ahead by a couple of points in xP. Given this fact alongside Mertesacker's much higher ownership number (15% vs 1%) and Sagna's slight discount, Sagna looks like the better pick if you were choosing one today, though Mertesacker owners shouldn't feel overly rushed to move him.

Aston Villa
There's really nothing to see here and if you want to invest in this back line you should do so based on playing time and price tag. That could lead one to settle on Baker given his 3.9m price, assuming you are confident on him holding off the challenge of Clark when Luna resumes his left back duties. This isn't a great defense but they've been reasonably good both at home (-1% SiB +/-) and away (-3%), but don't expect to get much on the attacking side of the pitch from your Villains.

Cardiff
Caulker is the only defensive player to notch any points, and coupling that with his name recognition leads to a potentially dangerous situation. Four total attempts, with two on target strongly suggests that his two goal haul to date has been fortuitous and thus that 0.9m premium over Ben Turner looks unjustified.

Chelsea
Ivanovic leads all defenders in xP to date with a very impressive 17 and managers have done well to recognise this, with a 25% ownership already racked up. With a risk rating of 1.2, he looks as safe as anyone in this team and the other 25% of managers who currently own Terry, or particularly Cole and Luiz, should strongly consider making a move to Ivanovic next time they have a spare transfer (or use their wildcard).

Crystal Palace
Delaney owns a slight advantage in xP here, but not enough to justify his higher price tag. If you are interested in this defense (hot tip: you shouldn't be) then Moxey - who boasts a perfect risk rating of 1.0 - is your man.

Everton
To date, this one is a no brainer. Coleman trails Baines in actual points by five but that total is far from enough to justify the extra 2.2m required outlay. Add in the fact that Coleman actually tops Baines in xP and you see that the young Irishman should be the pick here. One caveat which the model doesn't account for is Baines' threat from the spot but it's highly unlikely that Everton will earn enough spot kicks for Baines to deliver superior value to his cheaper colleague. The 17% of owners still holding Jagielka - who offers a reasonable though unexciting attacking threat - should consider a move to Coleman when re-shuffling their pack.

Fulham
You really don't want to touch this entire team right now and there's nothing here to change that well reasoned opinion. Riether enjoys a marginal advantage in the attacking threat column but is well overpriced at 5.0m, even if he does carry a low risk rating. Just don't bother, please.

Hull
Davies boasts by far the best xP and actual points to date but seeing as you're surely only employing a Hull defender as a minimum price bench filler, 4.6m seems too steep a price to pay for only a marginal attacking advantage. This isn't a bad defense (SiB +/- of -2% at home and away) and they certainly hold value as 5th defender types but I'd personally lean towards one of the 4.0m options with Rosenoir looking nicely settled in this lineup at right back with Elmohamady moving further upfield.

Liverpool
Glen Johnson has been the best attacking threat to date, yet hasn't been rewarded for his efforts so far. Purely on this added threat, he doesn't appear to justify the extra cost, but given his added security in the first team (he's yet to be benched and his risk rating is only impacted by injuries) it might just be worth looking at Johnson if you either don't have Mignolet or want to double down on this useful unit. If Cissokho really locks down that left back spot it becomes arguable that Johnson's superiority in xP is insufficient to justify the extra 0.7m outlay but for now the Englishman just about holds the edge.

Man City
Not unexpectedly, Kolarov leads this team in xP yet - again, as expected - it's his risk factor (2.8) which renders him very hard to own unless your team budget has swelled to the point when you can routinely sit a 5.3m player. Even then it would be hard to own him as you're never quite sure who will start but if you feel you have a good read on Pellegrini's team selections, it's hard to argue with Kolarov's upside. Elsewhere no one really excels and you're faced with a contest between Nastasic and Zabaleta who are closely matched in terms of risk factor and attacking points potential.

Man Utd
Purely on attacking threat, Evra is just about worth the extra expense over his cheaper colleagues, but when you factor in his risk rating, he becomes even more attractive. Jones' occasional deployment in midfield has been something of a non-issue to date with the utility man failing to offer much going forward even when deployed further upfield. At 0.5m cheaper than Evra he's a tempting proposition though with Rafael on the mend to vulture a large slice of the right back minutes, the ever reliable Frenchman remains a solid investment.

Newcastle
Putting this week's poorly timed suspension aside (the Magpies get Norwich at home next), Debuchy is the clear pick here and is one of the more extreme outliers in this piece. He enjoys a perfect risk rating, leads the team in actual attacking points which are totally supported by his xP, yet he's owned by just 1% of owners, only good for 3rd on his own team. This isn't a great defense so if you're planning on benching a Newcastle player most weeks then perhaps Yanga-Mbiwa at 4.4m makes some sense, but if you plan on starting him, Debuchy's high floor and ceiling make him a useful pickup.

Norwich
No one really stands out here and thus it seems prudent to defer to risk rating rather than attacking potential, which would point us towards Turner as the best investment here. Whittaker's owners - presumably not paying attention or putting out other fires - should obviously look to divest with their man offering neither security nor upside.

Southampton
Lovren's 11 attacking points are nice, but his price is getting dangerously high and if you're looking to buy now, you're too late. Clyne should be a consideration given his significantly lower price tag and increasing security (he's played every game since GW4), ahead of Shaw who seems to face a more sustained threat from Fox. At 5.4m, Fonte might be the 'Goldilocks' option with a nice balance of security, price and upside, though if pushed I would personally lean towards the potential value of Clyne.

Stoke
Huth and Shawcross just about justify their half million premium over Cameron and Pieters, though it's probably close enough that you wouldn't rush to make a move if you owned either of the full backs. Fans of differentiation will want to note Huth's 2% ownership versus Shawcross' 10%.

Sunderland
Bardsley's heroics this past weekend catapult him atop these rankings, yet his risk rating suggests he's all but impossible to buy into. Sunderland have been a very solid defensive unit at home and there's room to add a Mackem as a 4th / 5th rotation type defender, yet it's hard to really pinpoint anyone who offers too much excitement. Looking purely at this team, O'Shea's low risk profile looks appealing, but higher upside can be found on other teams in his price bracket and thus if you want to buy in, you might need to take a calculated risk that Brown or Bardsley can lock down their places at a reduced cost.

Swansea
Chico's position on this chart will surprise many (include your humble blogger) as Davies and Rangel often impress going forward for Laudrup's team. This isn't the solid unit we saw for much of the last couple of seasons, but at 5.0m Chico's attacking upside, playing time and at least some promise of defensive value make him an intriguing option.

Tottenham
This one isn't so much obvious who we should pick as much as who we shouldn't. At 7.2m Vertonghen is valued as a defensive player who contributes big time attacking scores on a regular basis yet he's not managed to achieve that in either the actual (3) or xP (5) columns. He's essentially offered the same profile as Dawson at a 1.8m premium which is essentially the same as choosing a 5.4m scrub over Rickie Lambert.

West Brom
With Jones' injury McAuley's overall profile now looks quite promising and he just about deserves consideration despite some discomfort in paying 5.4m for him. West Brom have a good defense though, especially at home (-16% SiB +/-) and McAuley offers a sufficient upgrade over his peers to make that 0.5m worthwhile.

West Ham
Reid leads the team in xP and ownership (6%) but it doesn't look like the former justifies the latter. We saw plenty of early turnover in this team which has limited the risk rating of some players, but with Rat and Tomkins playing the last six games, they can probably be considered to be reasonably safe in Allardyce's first team and thus their lower price tags make them more attractive compared to the comparatively pricey Reid. Collins - who has yet to be voluntarily benched - looks to be the best value of all, assuming he can put his injuries woes behind him for a sustained period, though be forewarned that you are signing up for very little attacking threat.

Thursday, November 7, 2013

Will some players always underachieve?

We had an interesting comment from a reader this week regarding the visualization posted plotting actual points with expected points. My proposition was that the players whose xP trailed their actual points by a distance were likely undervalued by the market, and while we wouldn't suggest they will somehow "make up" those points left on the table to date, we would expect their production to take an uptick assuming they continue to get chances and playing time at a relatively consistent rate. The reader had a different view:

"When I look at this chart I don't see underperformers or overperformers all I see is players on form who are capitalising on their chances (Ramsey and Rooney) and players who are of such quality that they will always out perform the normal (Aguero and Yaya) . . . I believe that if you reconstructed this table after xmas with a start date of tomorrow then the same players would occupy the two sides."

It's a fair proposition and one I wanted to examine further. I think there's a general discomfort with the idea of regressing players' production to the mean as it seems to suggest they are all created equally. A couple of responses to that:
  1. For conversion rates which appear to be repeatable year on year, such as shot on target percentage (SoT%), we regress players to their own historical rates (where available). This means that if we say Olivier Giroud has an unsustainable SoT%, we're not saying his is too high compared with Danny Graham or Frazier Campbell, we're saying it's way above his own historic rate.
  2. For conversion rates where we do regress to a league average (or at least use league average in a weighted average), it's because I haven't seen any evidence that players can consistently perform above the average in that given rate. The classic example is goals per shot on target (G/SoT) which tends to regress close to a mean for most players, with only a couple exceeding the average for more than a couple of years in a row (and that would be expected even if we were talking about a totally random event). There might be some repeatability there, but it's a lot less than most would expect based on purely on notions like "form", "class" or being "clinical".
The good news is that this is fairly easy to test. Below we've plotted players' +/- score as of this week (which shows the difference between their actual and expected points with a positive score meaning their expected exceeds their actual) against the same metric from the midway point of last season. I picked that point in time based on the reader comment about Christmas but I'm fairly confident a similar conclusion could be drawn from pretty much any two comparable samples:

The first observation is that we see very little correlation from year to year. 10 players outperformed their points total last season by at least 10 points, yet only one of these (Podolski) has managed to outperform his total to date by even 5 points. Similarly, eight players underperformed their underlying stats by 10 or more points last season, and of these two (Lambert and Cisse) have once again failed to match their live up to expectations. On the flip side we've seen players like Aguero, Rooney, Lallana, Suarez, Michu, Walters and Fellaini benefit or suffer from huge reversals in fortune over the two samples.

One of the things I love about sports writing is that it can be a gateway into so many interesting subjects, and while I'm not learned enough to talk about most of them here, I would venture that there is an element of bias regarding the way we judge the above. When a player like Ramsey explodes in a small sample, we tend to quickly absorb that information into our collective psyche and it becomes the new self evident truth that he is a great player (despite several seasons of reasonable yet unspectacular play, at least from a fantasy perspective). We then place too much weight on these recent events, much like how people stop swimming after a shark attack, despite the fact there are countless things more likely to really kill them that they ignore every day. I believe the term for this specific type of bias is referred to as the availability heuristic.

In the chart we see Aguero has the second highest +/- score for 2013 and one could rationalise that being due to his superior skill and quality teammates. Indeed, that's possibly true to a point. However, he had those very same skills and most of the teammates last year too, yet was actually one of the biggest underperformers last year, serving as a constant source of frustration for his owners. Or take van Persie. Last year he ascended to a new level and was casually thrown into conversations alongside the best in the world, and thus the fact he outperformed his xP by a full 13 points through half a year could be discounted as him simply being better than everyone else. Fast forward 10 months and we have a player who has only just caught up to his xP total for the year, having suffered through some bad luck these past couple of months.

As a final check, the colour coding relates to the players' team's league position ranging from 1st (green) to last (red). I wondered if we'd tend to see players from the better teams show an ability to repeat positive seasons as they benefit from more quality chances per game. I guess this works to a degree in that those in the bottom left quadrant generally play for better teams, yet there's not enough here to really draw any solid conclusions.

It's always good to challenge forecasts like the ones you find in these pages - especially the ones found in these pages! - but caution should also be exercised when dismissing data which contradicts our current view of the game. There are certainly aspects of a player's game which can consistently be above average (SoT% for one) but others seem far less repeatable. The current iteration of the model adjusts for these differences and thus that's why we're going to see turnover in the players who over or underachieve expectations. 

Points versus expected points

The below chart is something I've posted before and am tweaking for the new website so I thought I should post it now and get your feedback while also hopefully providing a quick view to identifying some players to research further:


Sunday, November 3, 2013

Gameweek 11 Preview

Post any questions in the comments below, on Twitter or on Facebook and I'll get to the best ones before this week's deadline.