Shots On Target Difference
Last April, I wrote an article looking at how 'shot difference' (shots for minus shots against) and 'goal efficiency' (conversion percentage of goals scored minus conversion percentage of goals conceded) can give a good indication of how well a team is controlling their games (and you can read it here).
I later read this post by James Grayson, which demonstrated what chance a team has of being either in the top four or relegated, based on their 'total shot ratio', which I also covered in the above mentioned piece. It's interesting to note that the figures show that Liverpool have an 80% chance of qualifying for the Champions League this season; unfortunately they are clearly in the other 20%!
Now, thanks to an article on the Sky Sports website, I have the shots on target figures for the Premier League this season, so I can revisit my above article. The conclusions should be more robust, as 'shots on target' has a stronger correlation with success than 'all shots' does.
I have run the figures from my last article on the matter, and found that shot difference (SD) and goal difference (GD) had a 77.2% correlation in the Premier League last season. The shots on target difference (SOTD) figures from this campaign show a 79.7% correlation, suggesting it is a slightly better indication of how well a team is doing. Of course, a sample of only twenty is not ideal, so I aim to collate more data for a future article.
The below graph shows the GD and SOTD figures for this season, with a few key teams annotated:
The graph shows that Arsenal, Chelsea and Manchester United all have a superior goal difference to Liverpool, despite having a lower SOTD. The reason for that, is that they all score a higher percentage of their own shots, and concede a lower percentage of their opponents':
From a Liverpool point-of-view, the key headline statistics at each end of the pitch are:
- The Reds have had the seventh most shots on target, but only the eighth best conversion percentage. However, they have improved by an impressive 9% on last season, and are 1% above this season’s Premier League average. My theory is that the improvement is down to better shot placement, and I will be investigating that in a furture article.
- Considering their defensive issues, the fact that Liverpool have given away the third fewest shots on target is encouraging, though in my opinion a combination of Reina’s poor form and the high quality of chance the Reds often give away means that Brendan Rodgers side have the fourth worst conversion against percentage. It’s also 5% worse than it was for Liverpool last season, and 5% below league average.
It's interesting to note (using the data on WhoScored) that Liverpool have given away a smaller percentage of opposition shots in their box than any other Premier League side this season, as well as the fourth fewest shots in total. That their opponents score such a high percentage of those shots demonstrates to me that Liverpool are giving away far too many clear-cut chances.
I still believe that Brendan Rodgers has made progress overall at Liverpool this season, but they desperately need to tighten up at the back next season if they are to make the most of their 80% chance of finishing in the top four.
Related articles you might like:
Shot Difference and Goal Efficiency – A piece on how efficient each Premier League team is at both ends of the pitch.
Shot Placement: Gerrard’s Impact Against Everton – The captain bagged a hat-trick against the Toffees, but what part did his shot placement play in that?
Shot Placement: The Suárez Show – Liverpool beat Norwich City 3-0 at Carrow Road, and this explains why.
Please check out my other articles, and follow me on Twitter or via Facebook. Thanks.