Does Passing Accuracy Predict Results, part II

By Bill Farnham

Hopefully the previous piece was pretty clear and you came away with a better understanding of the Liverpool team. In this article I’m going to review some of the conclusions that came out of the previous piece and see if I can use chalkboards, heat maps, and action area diagrams from Squawka.com to verify whether or not I was right.

First, a summary of the points from the previous article:

Point No. 1:
“There is a moderate negative correlation between Glen Johnson’s Passing Accuracy percentage and the points that Liverpool earns from a match.”

My interpretation for this point is that in situations where Johnson is not moving forward and pushing higher up the pitch, i.e. in situations where his passing is more likely to be short and less adventuresome, Liverpool is less likely to win.

Put another way, if Johnson is pushed back by an attacking winger and opposition fullback pairing, his passing tends to be more sideways and backwards and lower risk, not the type of passing that has a great impact on goal scoring, and subsequently Liverpool are not as likely to score or take maximum points from the match. In situations like this Johnson is presumably defending more and not contributing as much or as effectively to Liverpool’s attack.

Point No. 2:
There is a moderately strong positive correlation between Glen Johnson’s Passing Forward percentage and Liverpool realizing points from a match.

My interpretation for this point is that as Glen Johnson is making more forward passes, passes more likely to be defended against, his PA percentage will decrease, but Liverpool is more likely to score or take points from the match as they are attacking more. In situations like this, Johnson has more freedom to bomb forward and contribute to the attack.

Now let’s figure out how to determine if the above interpretations are correct.  To prove or disprove the first point I need to look at Johnson’s passing in a match that Liverpool lost.  I would expect to see predominantly short, safe passes on the passing chart. Here’s the passing chart from Liverpool’s loss to Manchester United at Anfield on September 23, 2012, when Glen Johnson was matched up against Antonio Valencia, one of the better wide players in the Premier League:
In this match Johnson completed 86 percent of his passes, his fourth best AP percentage for the season thus far.  Squawka.com’s passing analysis indicates that Johnson tried only 2 long balls and no through balls, and that he did not have any key passes. The chart above also shows that the majority of passes that Johnson made were in the area between the first and the middle third of the field, which would indicate that he is winning the ball or receiving the ball in a slightly more defensive position. So far this evidence seems to support the general hypothesis, namely that in a game where Johnson has significant defensive responsibilities, his passing will be shorter and safer, and Liverpool is less likely to win. I would also expect to see that Johnson did not spend a significant amount of time in the opposition half because of defensive responsibilities.

To check on this let’s look at the heat map and action area graphics from Squawka.com:
In the heat map Johnson clearly seems to be spending more time in the first  and middle thirds of the field than the final third of the field. The action area graphic breaks down the percent of time spent in each section of the field (again from Squawka.com):

So far it looks like everything is dovetailing nicely with my expectations.  Let’s look at the road loss to Tottenham Hotspur on November 28, 2012 to see if the pattern continues.  In this match Johnson came up against Gareth Bale, one of the fastest and most dynamic wide players in the Premier League. Johnson completed 82 percent of his passes, slightly below his season average of 84 percent, and made 1 key pass.  He did not play any long balls or through passes.  The passing chart below shows that Johnson’s passing is spread more evenly across the entire field of play, and not as defensive as against Manchester United.
The heat map tells a similar story (note that Liverpool went down 2-0 after 16 minutes and it begins to make a lot more sense) as it appears that Johnson spent a greater amount of time in the opposition half of the field than in his own.  Liverpool were definitely chasing the game, having conceded two early goals, and Johnson was involved in the attacking build up.
The action areas graphic highlights the differences between this match and the one against Manchester United.  Johnson spent a much greater percentage of time further up the pitch and drifted into the center slightly more as well, especially in the final third.
What’s the conclusion then? In the Manchester United game, a game in which Liverpool led briefly and then surrendered two goals, the second in the 81st minute to van Persie, Johnson played a more defensive role, primarily concerned with keeping Antonio Valencia in check and giving anything away. His PA percentage was slightly higher, while his PF percentage was decidedly lower. In the Spurs game,  Liverpool surrendered two early goals and had to try and chase the game to salvage points from the match. As a result, Johnson’s passing and positioning much more closely resemble a match in which Liverpool is pressing forward and attacking an opponent, something that the team was forced to do by the early goals that Spurs scored.

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