Liam Kelly reviews the Premier League action from a data perspective, highlighting points of interest after the weekend round of matches.
The aim of this weekly column is to provide standout stats from each round of fixtures, to use underlying numbers to identify recent trends, and to inform punters with tools to improve their betting on the Premier League.
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Spotlight on spot-kicks
In the absence of many 'micro' talking points — at least from a data perspective — from the Premier League matches, an opportunity arises to look at a 'macro' motif that had an impact on games and the advanced metrics we can apply to it.
Penalties, of course, were the deciding factor in a number of the nine fixtures this gameweek, lining the narrative of the weekend.
Indeed, more penalty goals (6) were scored than all other methods of scoring combined (5) on Saturday, affecting the result in every game involving the forecasted top-four at the end of the season.
Thanks to the sheer amount of data available on the subject, an accurate total of 0.80 expected goals (xG) is attributed to every spot-kick in the Premier League, but there is greater interest in looking at the value of the penalties scored in the context of the games this weekend.
Brentford opened proceedings with another Friday night victory, beating Watford thanks to a very late Bryan Mbeumo penalty. The 95th-minute winner bumped up the Bees' expected points from 1.04 xP to 2.96 xP — highlighting the importance of that single event.
- Expected points (xP) measures the number of points a team could have expected to have taken from a game, expanding upon the expected goals (xG) predictive model to give in-play values.
There are many factors that can influence expected points (xP) during a match. In Brentford's case, it was mainly the clock, with Watford having almost no time to respond. Pre-match probabilities, prior in-game events and the scoreline are other details of note.
For instance, Manchester City and Liverpool were heavy favourites to win against Wolves and Aston Villa respectively and were fairly dominant throughout their matches with time left to spare, giving their xP total a higher floor before each penalty.
Raheem Sterling's 66th-minute penalty moved City's xP from 2.05 xP to 2.86 xP, while Mo Salah's 67th-minute equivalent lifted Liverpool's xP from 1.82 to 2.73.
Chelsea could be seen as a victim and/or beneficiary of all of the above, given more than enough time to respond to Raphinha's penalty, before dropping from 2.71 xP after Jorginho's penalty following Leeds' equaliser.
Eventually, Jorginho's second spot-kick in the 94th minute moved the Chelsea needle from 1.28 xP to 2.88 xP, and with it, avoiding the loss of valuable ground at the top.
Granted, some of these are pretty obvious, gaining the added two points for a victory compared to a draw, but it is interesting how one single event can change things, even if it is as substantial as a late penalty.
Even the small matters can make a big difference — across all sports.
What would Lewis Hamilton's expected points total have been with six laps remaining in the Abu Dhabi Grand Prix on Sunday if such a model existed?
A crescendo of driver error, race director decision and subsequent strategy turned the title on its head, handing Max Verstappen the Formula 1 World Championship. Before that, every rotation of the wheel burned away what little hope remained for the Dutchman.
In time, the 1.60 expected points that hinged on Jorginho's penalty could be the difference between a Premier League title or not for Chelsea, and the 1.92 on Mbeumo could be the difference between survival in the top-tier or relegation to the Championship for Brentford.
It really makes you wonder how some people can do without the drama that sport brings. Sometimes, it is vivid and immediate. In the case of Premier League penalties this weekend, only time will tell.
