Tuesday, November 13, 2012

Trending: Shots in box

One of the measures that goes into the team model looks at how each team has performed against their opponents compared to how the league fared in that same fixture. So, if for example, Southampton at home are surrendering nine shots inside the box per game and Everton come in and rack up 12 SiB, they have 'overperformed' by 33%. Rather than look at the standard measure of form (i.e.goals) which focuses on the results rather than the process, we can look at this data and see if teams are playing consistently or trending in one direction or the other. The added benefit to this metric is that it is opponent adjustment so 'form' doesn't get blurred by simply having a run of easy or hard games.

Although the model measures shots inside the box, outside the box and those on target, I have found SiB to be (a) predictive of future success (see graph below) and (b) generally consistent for a given team (unlike SoT which can be affected by crazy on-target rates like Steve Fletcher earlier in the year given the tiny sample sizes involved):

Note that the correlation and line of best fit is fairly strong with only a couple teams varying significantly from the average trend. I'm therefore fairly confident to say, as a general rule, that SiB will lead to goals on a fairly consistent basis, though we might need to point out the out exception where required.

Attacking SiB
If we plot the weekly over/under performing numbers and then create a line of best fit we can identify potential trends as to teams who might be declining or improving. Now, the below graph is highly simplified and I understand that we need more info if we are to draw any certain conclusions about what the data is telling us, such as whether certain players were missing for a given fixture or how inconsistent they've been within the trend. However, I like this analysis to give an indication of where we should focus our attention, so long as you accept it isn't the single answer to which team's are improving/declining:

Every team not highlighted here have essentially been flat all year so there wasn't much more to say about them. The above teams shows the biggest variances, with three strong improvements and four sharp declines.

  • Man City - the narrative has generally been that City are struggling immensely this year and haven't really improved of late, perhaps even declining (honestly, my frustration with Mancini may have led me down this erroneous path too on occasion). The data doesn't really tell this story though. They managed just seven SiB against Swansea in GW9 but otherwise their recent games have seen them outperform their opponents by 53% (WBA), 79% (WHU) and 57% (TOT) and while the goals haven't exactly flowed, for them to continue to score goals at their current rate per SiB would see them well underperform the trendline from prior year which just doesn't seem likely based on the profile of their forwards (compared to, say, Suarez, who is at least part of the reason for Liverpool's outlying stats last year).
  • Everton - I think there's a perception that Everton are sort of overachieving and scraping together a surprising set of good results but while the above trend shows a slight decline it (a) still places them ahead of everyone but Man City (including those teams not shown) and (b) the trend is somewhat skewed by a couple of poor outings, including this week's 14 SiB against Sunderland (amazingly that's only 2% over the league average) and their eight SiB against Wigan (-6% versus league average). In short, I see nothing to worry about here and the 'decline' is more a case of not having crazy demolitions of teams (GW5 - 24 SiB, 157% overperformance vs Swansea) than a sign of any real decline.
  • Fulham aren't a particularly well praised team and they've really just ticked along this year, not making much noise outside of Berbatov. You can only really play their players at home thus making them tough to own, right? Nope. This year their 12 goals on the road ranks second in the league behind only Man Utd, as does their 24 total goals. The last four gameweeks have seen them crush Villa (+115%), Reading (+41%) and Arsenal (+75%) with the only blemish being the Everton fixture (-58%). As noted in this week's lineup lessons, it's still tough to find consistent options in this lineup but if their form continues on anything close to this trajectory it's worth scouring this team for value.
  • Liverpool - We know that Suarez has been great, but as was the case with Newcastle last year and so far this year, the data suggests that they play of one player might be covering over the cracks. After opening the season with big SiB totals against Arsenal (+60%) and Sunderland (+68%), Liverpool have really struggled on late failing to really excel in any of the last five games. There probably aren't a ton of options in this side anyway and Suarez has shown he can survive or even excel despite Liverpool's struggles, but this data suggests that at least some caution should be exercised before getting carried away with Suarez's excellent returns of late.
  • Southampton - Southampton's struggles have been more a symptom of not punishing the weaker sides rather than struggling against the better teams so there isn't too much concern here. The last two games (-32% vs WBA, -50% vs SWA) are skewing this ranking a touch and while two games are a reason to panic, this is a team who needs to monitored if you own or are tracking Lambert, Lallana or Ramirez.
  • Swansea - Readers will know that I've been a huge fan of Swansea's workload over the past season and a quarter but the data here is troubling to say the least. The last six games have seen then underpeform league average by at least 20% in all but one game, including three times underperforming by 50% or more (Stoke, Chelsea and Southampton). The price of some of Swansea's players is sufficiently low to keep them as useful options but this is another warning shot to those not discouraged by Michu's worrying underlying stats.
Defensive SiB

  • Man City - City have been trying our collective patience of late, but this suggests that there's reason to at least keep them in mind, even if you want to temporarily move on at the moment. So far this year they've only underperformed the league average once (GW7 Sunderland +4%) an have performed well in the last four (-50%, -55%, -29%, -29%). Their conversion rate of few SiB into clean sheets hasn't been great but on this basis the chances should continue to come thus suggesting my frustration to the point of dismissal of this side was premature.
  • Man Utd - As with City, United's defense has been frustrating so far this year and giving up goals against the likes of Stoke at home and Villa this week was disappointing. Again though, the data looks useful so the likes of Rafael remain viable options for the coming weeks.
  • Wigan - Not really considered a good defensive side, Wigan have really improved of late. After underperforming early on against Southampton (28%), Stoke (80%) and Man Utd (25%), Wigan have reallt turned it around of late, looking particularly good against Sunderland (33%), Everton (44%), Swansea (32%) and Tottenham (42%). After giving up a couple of goals at home to a solid but hardly elite West Brom side this week, it's clear that Wigan aren't ready to become every week starters in the coming weeks but for the first time in memory they are becoming a viable defensive option.
  • Aston Villa - not much fantasy impact given that Villa are hardly great defensive options anyway, but I had been flirting with them after a couple of decent performances so this is a bit of a turn off. Even that clean sheet against Sunderland came with them surrendering 10 SiB, 67% higher than their usual woeful performance. 


Snorre said...

This was a nice writeup, thanks

CDI said...

This is the G.O.A.T Fantasy football blog. I check it several times a week and he never disappoints.

Chris I notice you have no Man U offensive cover despite your model saying they will Beast over the coming weeks. Do you plan to move heaven and earth to get RVP or will you be happy with Rooney? I currently Have both but not sure it was a geat idea in hindsight.