Peterborough United: A statistical look at recent failures to return to the Championship. Part five: 2019-20 season. ‘Much Improved Defence & an Unfortunate Conclusion’

Data is only readily available for the last five seasons so we will cover a season a day from Monday to Friday. Today (September 8) James covers the 2017-18 campaign.

Key:

Expected Goals (xG): A model which measures the likelihood of any individual shot being scored, with 1 being a 100% chance of scoring and 0 being a 0% chance of scoring. It takes into account factors such as angle, distance and body part of the shot taken.

Expected goals against (xGA): As above but for shots conceded.

Expected Points (xP): The number of points a side would have collected if the side who had the better chances to score had won, based on each team’s xG data.

Per 90 (p90): How often a team or player performs a certain action every 90 minutes of game time.

Key Pass: A pass or cross which creates a clear situation or opportunity for a goal but the receiving player misses this chance.

Deep Completion: A successful pass (not cross) that finishes within 20m of the opposition goal.

2019-20: ‘Much Improved Defence & an Unfortunate Conclusion’

If the 2018/19 season can be summarised as one of overperformance and luck then the opposite is true of the season just gone. Whereas Posh were lucky the finish as high as seventh in the 2018/19 season, last season Posh were very unfortunate to have not finished higher than that same spot.

Posh finished the season with an expected points total of 68. That figure would have seen Posh top of the table when the season finished and second after the final PPG calculations are taken into account. Moreover, the season ended just as Posh we’re finding their best form. A combination of new signings and a change in system meant Posh were at their very best just as the season was approaching its business end.

Much of Posh’s success owed to their exceptional attacking unit. Posh scored more goals (68) than any other side in the league, their xG per match (1.54) was the fifth highest in the league, while Posh took the sixth highest number of shots per game (12.69) with the best shot accuracy in the league (42.6%), which is a truly incredible stat and the only time any League One side has recorded a shot accuracy above 40% throughout this five year sample). If there is a criticism of Posh’s attack however, it’s that they drew a blank in eight matches. Of the sides who finished in the top six, only Wycombe Wanderers failed to score on more occasions (10).

Another impressive aspect of the season was Posh’s improved defensive performance, especially in the context of signing an entirely new defence and goalkeeper in the summer. We can measure defensive performance on a number of basis. On the most basic of metrics, goals conceded, Posh ranked 10th in League One, their best ranking of the past five seasons (13th 2018/19, 14th 2017/18, 15th 2016/17, 20th 2015/16). However, goals conceded is not always the best measure of a side’s defensive performance and it is in the more nuanced measurements where Posh showed the most significant improvement.

Posh gave up the ninth fewest shots in the league at 9.84 p90 at the lowest xG per shot in the league of just 0.091, meaning that in general the defence forced the opposition to take shots from positions whereby they were unlikely to score. This gave Posh the best xGA per match in League One (0.97). On paper, defensively Posh performed as well as any other side the league. However, Posh conceded more goals than expected at 1.14 per match, which equates to roughly six more goals conceded than expected during a 35-game season. We can look to some early season goalkeeping errors as a part explanation for this as well as some good finishing from the opposition.

One thing that did let Posh down defensively was that when they did concede, they often conceded more than once. There is a truism in the football data community that it only takes one moment to concede a goal, but defensively astute sides will rarely concede more than once a game. It’s well documented that Posh kept the most clean-sheets in the league (15), however what’s been less well reported is that they conceded two or more goals on 13 occasions, the 9th most in League One. Maybe then, despite having one of the best defensive records in the league, Posh weren’t quite consistent enough defensively. When Posh were performing well defensively they were excellent, but they had a few too many off days resulting in some crucial dropped points. Did this perhaps ultimately cost Posh a playoff spot?

There were of course other areas whereby Posh could have done better and therefore still reached at least the play-offs regardless of their misfortune with the early curtailment of the league. Fergie’s midfield diamond came in for a lot of criticism from fans and when we look at the data much of that criticism appears justified. After a quick start Posh’s performances dipped in the diamond, improved after switching to a back three, tailed off again in the diamond, before improving exponentially again once a side now including Reece Brown, Sammie Szmodics and Jack Taylor reverted to a back three system. The second table shows Posh’s performance data when starting in a 3-4-1-2 formation compared to a back four (diamond, 4-4-2). Again, Posh posted significantly better attacking and defensive numbers, while collecting more points, when lining up in a back three.

It’s important to also consider Posh’s over-reliance on Toney and subsequent struggles when he was absent. The only blip during Posh’s last nine matches came when Toney was suspended for games away to Burton Albion and Fleetwood Town. With Eisa up front alongside Dembele Posh controlled possession in deep areas but struggled to get possession in dangerous positions or create chances. Posh mustered an average non-penalty xG of just 0.35 (season average 1.37) in those two games, attempting just six shots in each (season average 12.69).

Dominating possession, but failing to score was something of a specialty for Posh. Posh fared much better when they had less possession in games and could transition to exploit the space left by more open opponents. Posh collected just 12 points from the 12 games when they had more than 53% possession, but came away with 22 points from just 11 games when they had less than 47% possession.

Posh’s only wins when they had more than 53% possession came in a 3-4-1-2 formation in home games against Southend United and Wycombe Wanderers both 4-0, and 2-1 away to Gillingham, when Posh converted early from a diamond to a back three. The midfield additions of Reece Brown, Jack Taylor and Sammie Szmodics also helped in this regard, as they added the composure, drive and improved decision making in the opposition half required to break down sides in a deep block. When playing with a back four Posh collected just three points from the six matches they had 53%+ possession, demonstrating just how badly Posh struggled to break sides down before switching system, primarily due to lacking the necessary width required to stretch packed defences.

So Posh’s 2019/20 campaign as one of vast improvement and bad luck. However, we must also acknowledge that the formation handicapped the players for a little too long for them to make up on lost ground and that Posh started the season without the necessary quality in midfield to play an effective possession game.

Can Posh make 2020/21 the season when they finally crack the playoffs or better? If the end of last season is anything to go by the certainly have all the tools do so.