Monday 15 July 2013

FSCORE (more analysis)

Following suggestions from a couple of wise readers this post is going to deconstruct F.SCORE some more, to see how it's accuracy varies when modelling FPL points based only on a player's statistical performances, by

  • GW range through the season - do stats paint a better picture of FPL points midseason? (thanks to Lucien for the suggestion)
  • FPL Points scored - how do stats explain points scored between high vs. low scoring players? (thanks to 2ndMan)
  • FPL Points vs FSCORE vs Team
There's also the small matter of the OMGFPLPRICELIST is released!  If you hadn't figured by now, I am blogging at InsideFPL which is a place for much more direct fantasy football content, the answers so to speak. This site will remain where the questions get asked ;) So please do check out InsideFPL for more from me. 

I'll have more of what the future holds soon enough but for now back to the hardcore stats!

F.SCORE vs Actual Points Through the Season
I've plotted Points Scored / 6GW and FSCORE / 6GW through the season to see how the model varies at different stages.

6 week rolling avg. 

At the start of the season FSCORE and Points hold pretty well but then actual points scored goes up quite suddenly around GW13-15 until GW27ish when it drops right down below.  In other words teams/players score goals at an expected rate per shot (etc.) at the season starts, mid-season they score more goals per shot, and then start missing loads at the end of the season.

Needs a fair bit more investigation this one!

F.SCORE vs Actual Points by Overall Points Scored
Points 0-75  R=0.90

Points 75-210   R=0.83

It's quite easy to see the correlation gets worse the higher the points scored, but thankfully not horrifically so.  There's definitely an unacceptable spread as pointed out in my last post at the 150pts mark.  I suggested last time that this could be due to Game State and Shot Zones but assists from set pieces or penalties will also factor heavily I think. 

F.SCORE vs FPL Points by Team
I observed last time that this spread featured players like Mata, Hazard and Tevez over-achieving their stats (above the line) and the likes of Jelavic and Cisse under the line, and hastily assumed that this was because the above-the-line lot were from freer-scoring teams.

In retrospect, this assumption needs testing and in truth I just went head-over-heels to take a closer look at Game State following 11Tegen11's own analysis. Back-tracking some then, let's take a look at how total F.SCORE for team's compare with their total FPL points..


This is pleasing and backs up the assumption that "truly better" clubs tend to turn their     chances (a.k.a. stats/FSCORE) into goals and FPL points.  Sunderland's little leap from the line needs to be checked out!

Firstly, quick-posts-before-bed seem to turn into epics! In general the correlations are still very strong between underlying player or now team stats and FPL points scored. There are significant variances from club to club (or elite club's players vs. non-elite)  and at different stages of the season and the aim of further analysis is to determine the data-driven factors that cause these variances and build that into FSCORE and Points Projections.
  • The FSCORE model works better for low-scoring players than high scoring ones.
  • At season start teams score goals and convert shots to point at closest to expected rate
  • Mid-Season they score more
  • End Season they score less
  • Players in teams who 'score for fun' (Utd) generally convert chances at a better rate than those who can be consider high scorers but easily "frustrated" (e.g. Liverpool)