Wednesday, 4 January 2017

How Dominant Are Chelsea's Halftime Record Chasers?

Chelsea travel to Spurs tonight needing a win to equal the record for the number of consecutive Premier League wins.

After 19 games, half a season, they have accumulated 49 points, beaten only by the 2005/06 Chelsea side, who gained 52 points and equalled by the 2003/04 Manchester United team.

In keeping with all of the traditional title challengers in the Premier League, Chelsea has put a lacklustre 2015/16 behind them and improved their expected goals at both ends of the pitch as the season has progressed.

It is an impressive reversal of fortunes, but it is also shared by their title challengers. Only Arsenal has shown a marked decline in their defensive metrics and of course Leicester, although the Foxes have been replaced by a resurgent Manchester United.

Chelsea are therefore worthy favourites to regain the title in May 2017. In simulations of the remaining matches, they are odds on to finish top of the pile.

But where does the current halfway house, Chelsea lie in the Premier League role of honour?

Points won is a natural starting point, but that neglects to account for the closeness and quality of challengers.

A better measure is the points per game won by Chelsea, expressed as a standard score, which attempts to account for how dominant a side has been using the characteristics of this particular season as a benchmark.

Chelsea (2016/17) is currently 2,06 standard deviations above the league average points per game prior to last night's results. Five teams are within 10 or fewer points of their current total, albeit after one game more, with the exception of their opponents tonight, Spurs.

By contrast, 2014/15 Chelsea had three fewer points than the current team, but had burned of a lot of challengers, with the exception of Manchester City. So arguably that was a more dominant mid term performance.

Similar comments apply to the other eight teams above Chelsea in the preceding table in terms of standard scores at halfway.

Check out the ultimate performance of the league leaders on Christmas Day based on their standard scores in this post from 2014

Monday, 26 December 2016

Palace's Pre Christmas Expected Goals Breakdown.

This time last year, Palace were 6th in the Premier League and the Europa League was being touted as a legitimate aim. 

This time around they're 17th and have embarked upon Sam Allardyce's return to domestic football after his unbeaten reign as England manager.

                   Palace's ExpG Breakdown for their First 17 Games in 2015/16 and 2016/17.

Some small sample sized bulges have appeared in the way they've dealt with corners and set pieces and the post kick quality of the shots or headers (in grey) have been less kind in 2016/17 than they were in 2015/16, but overall the cumulative expected goals are broadly similar for both periods.

Randomness partly made Pardew a hero in 2015/16 and unemployed a year later. 

Tuesday, 13 December 2016

Blocks Away.

I've written before about a side's ability to block shots, the latest post was here and Burnley's large number of blocks in the Premier League to date has attracted the attention of Twitter.

Blocked shots may be examined in the same way that expected goals may be calculated from modelled historical data.

I have used Opta data that is the raw building block to power Timeform's InfogoApp to model the expected blocks a side may make based on a variety of variables, most notably how central a shot or header is taken from.

The model was built using data from previous seasons and used to predict blocks in the 2016/17 season to date. It adequately passed a variety of goodness of fit tests on the out of sample data.

I have looked at both the number of goal attempts that are blocked by a side, as well as the number of their own attempts that are blocked. So each side has been examined from an attacking and defensive viewpoint.

             Expected and actual Blocks in the 2016/17 Premier League After Matchday 13.

As you'd expect teams either over or under perform compared to the most likely number of blocks based on an average team model.

After 13 games, Liverpool had 78 of their own shots blocked compared to an expected baseline of 73. An under performance, but not really suggestive of anything other than simple variance.

It's slightly less easy to dismiss Sunderland's 48 blocked shots compared to an expected value of just 33. The chances that an average team takes Sunderland's attempts and sees at least 48 of them blocked is less than 1 in 200.

A simulation of all of Sunderland's goal attempts to week 13 produces the above distribution and likelihood of those attempts being blocked. Sunderland's actual block count or above can just be seen at the extreme right of the plot.

On the defensive side of the ball, the Puliser Prize for blocking in the face of adversity, surprisingly doesn't go to his current side, WBA, but Everton.

58 blocks compared to a tactically neutral expectation of just 45 and a 1 in 100 likelihood, hints at some degree of intent.

And Burnley, as they home in on a ton? 89 is a lot, but compared to an expectation of 80, it is their hospitality in allowing teams to shoot that has raised the bar as much as a tactically adepted blocking scheme.

An average side would equal or better 89 blocks after 13 games, given the shots allowed around 14% of the time.