OOTP Developments Forums - View Single Post - 1871-2017 Defense Plus/Minus System

Garlon · 09-30-2018, 09:46 PM

I went ahead and calculated the FIP for every team 1871-2017. From this I was able to compare it to the league average runs allowed per 27 outs and determine how many runs above or below this a team was for a season. This is their expected Defensive Runs Saved for the season based on FIP. I then took a 3yr average of a team's expected DRS based on FIP and compared it to their 3yr average based on the PlusMinus system. The result was that the 3yr average was within 17 runs saved of the FIP expected. I did this because these are entirely independent ways of evaluating team defense and I wanted to see how well the PlusMinus system works. With regards to the difference, I think it may be small enough that a significant portion of those 17 runs allowed may just be to luck or a team having fewer/more opponents in scoring position against them, therefore their plays made above/below average may be worth slightly less or more than expected.

There are 2482 team seasons from 1901-2017 and 70% of them have a 3yr average difference within 20 DRS.

For example, if we look at the 1906-1908 Cubs their FIP DRS total for those seasons is 272 and their PlusMinus DRS is 265, a difference of only 7. This puts their average season difference between these at less than 3 DRS for those seasons.

This suggests that we have the data to properly model defense in OOTP.

09-30-2018, 09:46 PM	#7
Garlon Hall Of Famer Join Date: Jun 2004 Posts: 4,274	I went ahead and calculated the FIP for every team 1871-2017. From this I was able to compare it to the league average runs allowed per 27 outs and determine how many runs above or below this a team was for a season. This is their expected Defensive Runs Saved for the season based on FIP. I then took a 3yr average of a team's expected DRS based on FIP and compared it to their 3yr average based on the PlusMinus system. The result was that the 3yr average was within 17 runs saved of the FIP expected. I did this because these are entirely independent ways of evaluating team defense and I wanted to see how well the PlusMinus system works. With regards to the difference, I think it may be small enough that a significant portion of those 17 runs allowed may just be to luck or a team having fewer/more opponents in scoring position against them, therefore their plays made above/below average may be worth slightly less or more than expected. There are 2482 team seasons from 1901-2017 and 70% of them have a 3yr average difference within 20 DRS. For example, if we look at the 1906-1908 Cubs their FIP DRS total for those seasons is 272 and their PlusMinus DRS is 265, a difference of only 7. This puts their average season difference between these at less than 3 DRS for those seasons. This suggests that we have the data to properly model defense in OOTP.