A TSR Variation – DZTSR

Luke Griffin@SL_TeamTalk

This is going to be a short article about a metric I thought of today, similar to TSR. I want to keep it short and sweet, so enjoy.

Total Shots Ratio (TSR) is a metric I’ve written about here. It is an commonly used metric as it has a strong correlation with Goal Difference and points. If you outshoot your opponents you’re likely to win. It is also useful to use in match predictions. I recommend you read the article linked above to understand it if you’re not familiar with it.

It’s worked out as: Shots For / (Shots For + Against).

Screen Shot 2016-09-14 at 21.16.45.png

The two graphs above and below this are TSR graphs I’ve borrowed from   and @penaltyblog. As you can see the R^2 is about 0.67. Both graphs use lots of data points and shows how important TSR is in getting lots of points.

TSR James Grayson.png

I’ve thought of simple metric based on TSR. I thought of it today in my A-Level maths class. It may have been used before, or something similar to it but I haven’t read or seen anything. Please note I am not saying it’s ‘my’ metric  and that I have created it. But, I’ve never seen anything about it. I may thought of it myself, but I wasn’t the first so don’t think that I think I’ve found some revolutionary metric to replace TSR.

It is called Danger Zone Total Shots Ratio, or DZTSR. It is TSR but only counts for shots in the ‘danger zone.’ @footballfactman  has found in his SPAM Model that DZ shots have a 1 in 6 chance of being a goal. These are great shots to take and have good xG values.

Dangerzone.png

So, how good is DZTSR?

From the 58 data points I have included on this scatter graph I have found a R^2 of 0.813. That is an improvement of ~0.14 from TSR. Having a larger DZTSR is a larger indicator on final position in table than TSR. I think this is an important KPI when evaluating teams. TSR is still a good metric and I’m not at all saying it should be replaced, but this is also a useful metric in my opinion.

If you can see an issue with the idea please tell me. If you like the metric let me know, all feedback is appreciated. Contact me @SL_TeamTalk. If you every use this metric and tweet or write about it, tweet me. I’d love to read it.

DZ data taken from: http://cartilagefreecaptain.sbnation.com/2014/2/15/5409046/la-liga-shot-statistics

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