Saturday, December 16, 2017

Raising their game or feasting on the weak (or, which teams do players do well against)

However good a player projection system is, it will always have certain assumptions built in which require some judgement on behalf of the model's creator. This might include how much weight to put on recent games versus historic data or how much to regress team or player conversion rates back to a league or historic average. One such assumption I do not currently factor into my own model is which kind of games a particularly player performs well in. For example, if Harry Kane accounts for 30% of his teams shots inside the box and Spurs are forecast for 10 SiB then his forecast will be three SiB regardless of who the opponents are. The strength of those opponents is of course somewhat baked into how we get to the 10 SiB projection in the first place, but no attention is paid to whether Kane has tended to over or under perform expectations against weaker or stronger teams, or whether he's struggled against teams who deploy three centre backs.

The data below takes the first steps to trying to factor that data in. Let's look at Harry Kane as an example:


I think there is a perception among some that Kane hasn't punished weaker opponents this year, which probably arose having failed to net against Burnley, Swansea and Bournemouth at home to start the season. In terms of expected goals though, we can see that he has actually excelled in all but one of his easiest fixtures (GW11 vs Crystal Palace). Generally his chart is exactly as an independent observer would expect - with him putting the sword to weaker opponents but having less potential success against stronger teams. In Kane's particular case there aren't any huge lessons here - you're not dropping him against anyone - but I do think this is a data point against necessarily captaining him without much thought to Spurs' opponent.

Let's check in with a couple of other players who have interesting profiles, then the visualization is at the bottom of the post for you to play around with.

Lukaku
Lukaku is probably the name most synonymous with feasting on weaker opponents, and this is indeed borne out in this data. In 10 fixtures which rank as easier than average, the United front man has averaged 0.8 expected goals per game, compared to seven trickier fixtures in which he's averaged just 0.3 expected goals per game. In real life this is a problem for Jose Mourinho, but in fantasy terms it's arguably beneficial to have someone who is predictably good against weaker sides and struggles against the top sides as he becomes easier to transfer in and out of your team (or captain). From GW19-24 United face only one fixture that ranks significantly harder than average in terms of xG conceded, making the Belgian a better target than I think most people realise.

Richarlison
Richarlison is generally one of the most interesting stories of the season so far, and his data here doesn't disappoint. The Brazilian has absolutely dominated in his sides tougher games, amassing 4.5 xG in 9 games against above average opponents (scoring 3 goals in the process). Yet, in eight easier games he's still netted twice but based on significantly worse underlying data (just 1.7 xG). This could potentially be a case of Richarlison excelling awat from home, where his pace can be better utilized in that inside forward role, where as at home he is perhaps getting isolated out wide as teams sit back and make Watford break them down. I don't know if this would encourage me to drop Richarlison in GW20 versus a shaky Leicester side, but it would definitely make me feel better about starting him during his away games over the holiday break (perhaps even at Man City depending on the strength of your squad).

Lacazette
This is someone I have paid attention to for the past few weeks after making a panicked transfer to bring him in when I had a big pile of cash to use on a forward (but not enough to snag Lukaku or Kane). His data isn't super interesting but it does tell a cautionary tale about relying on a single data point to make a decision. If you sort all forwards by Opta's xG then through 17 weeks you'll see Lacazette sat nicely in fifth place behind Kane, Lukaku, Aguero and Jesus i.e. right where his price tag says he should be. However, teasing the data out a bit shows that he amassed 3.0 of his 8.4 expected goals in a single fixture (GW15 vs Man Utd), without which his total for the season would be down with Okazaki and Abraham. Now, it isn't totally fair to start cherry picking games to remove from a player's season but it's worth remembering to dig into the data a bit more as we progress into the halfway point of the season and not be overly reliant on season totals on their face. On the positive side, this data shows that for the most part Lacazette has performed well in his easier fixtures, making him somewhat worth keeping in mind should Arsenal enjoy a couple of good fixtures and you need a short term fix.

I wanted to share this viz now to try and help with transfers over the busy period but will come back to it with any further players of interest I find and a corresponding viz for assist potential.


Friday, December 8, 2017

The case for the other Liverpool wide man

If you are reading this then you almost certainly own Mohamed Salah. The Egyptian winger has been sensational for Liverpool this season and fantasy managers have responded by adding him to their teams by the thousand. At the time of writing is ownership is up to 51% and his value has increased by almost a million pounds since the game started. Today's piece is not about him though, but his colleague who hopes to operate on the other side of the field - Sadio Mane. A red card, injury and the form of Salah have pushed Mane out of many managers minds, but as teams begin to converge and differentiation becomes increasingly difficult, the Senegal star is a promising option.

First, a quick word on Liverpool. I think many people might be hesitant to invest close to 20 million on two Liverpool players (assuming you already have Salah) but I might suggest that fear is misplaced. They've scored just two goals less than Man United, four more than Arsenal, five more than Chelsea and ten more than Tottenham (based on Kane's 37% ownership and Eriksen / Ali's combined 30% ownership I'm assuming many manager out there has over 20 million invested in a Spurs duo). Liverpool are 3rd in shots inside the box, 3rd in total shots, 2nd in shots on target and 3rd in created chances. Opta's xG metric also places them 3rd with 29.3 expected goals to date.

While they can't match Man City's firepower, one major advantage to this Liverpool side is that there is no real question as to how the attacking options will line up when all healthy and not being rested. Salah, Mane, Coutinho and Firmino are a terrific foursome - as evidenced by some of the football on show against Spartak Moscow this week - and there's really no one knocking at the door and demanding minutes to replace them, other than when they simply need a break. There is a perception that Klopp is rotation happy, but putting aside his injuries and suspension, Mane has only been benched twice, and one of those games he didn't feature at all, which would have at least allowed your sub to come in. With Champions League football now behind us for a couple of months, I would be very surprised to see Mane miss more than the odd game over the next 6 weeks or so, and the fact he sat out against Brighton could actually be seen as a good thing, and he's less likely to be on the rotation block in the next couple weeks.

Contrast that with Man City where one of Aguero and Jesus needs to sit almost every week and the likes of Bernardo Silva and Gundogan are waiting in the wings to steal minutes from your fantasy men, or even across the city at United where only Lukaku and Pogba (when available again) are really locked into that team.

Let's have a quick look at some data for the elite midfield options, alongside a chart showing how Mane's ownership is lagging behind his production and certainly his potential:


Mane isn't in the same class as the top three picks here, although they each come with a drawback, be it saturation of ownership (Salah), price tag (Sanchez) or rotation threat (Sterling). Among the rest of the group though, Mane can certainly hold his own with my biggest concern being the lack of xA which might suggest he's a little one dimensional with his fantasy production. That said, his 1.8 CC per 90 mins and his 13% share of Liverpool's CC when he plays aren't bad numbers so there is hope that his assist threat might tick up a bit as he plays a few more games. I think the biggest shock name on here might be Hazard who doesn't seem to get much love from xG models. I suspected this was a flaw in my own numbers (my player projections don't tend to rate him as elite either) but it looks like he suffers under Opta's model too. This is worth digging into as to why Chelsea (and Hazard specifically) might be outperforming their underlying numbers, but however much you inflate him numbers, it will be tough to justify the extra 1.4m investment required to get the Belgium over Mane, based on these numbers alone (strength of fixtures and team coverage also need to be covered of course).

In the remaining six fixtures of 2017, Liverpool are set to welcome Everton, West Brom, Swansea and Leicester to Anfield, with a tricky trip to the Emirates being the only obvious concern, although even then Arsenal only rank 9th in xG conceded at home. After that there are a few tricky games over a relatively short period, but that's also getting into the new transfer period when wildcards are in play so I am personally happy to try and milk this underrated Liverpool side for the next month or so, letting everyone else put all their money into Chelsea or keep it in a Spurs side who have failed to hit the expected heights so far this year.