I hate for this to be my first post here, but I've been looking at ERA+ today, and it just doesn't seem right to me, at least not in context of OPS+.

I've always understood OPS+ to be OPS (technically the sum of its parts) in relation to league average, expressed as XXX% of league average.

In the simplest terms, a player with an .OBP of .300 and a SLG of .600 in a league with an OBP of .250 and a SLG of .400 would have a an OBP+ of 120, a SLG+ of 150 and an OPS+ of 170, assuming my math is correct.

But the accuracy of my math isn't my concern. My concern is that the SLG+ and OBP+ figures are quoted in relation to league average. If your OBP is .300 and the league is at .200, your OBP+ is 150, or 1.5 times that of league average.

However, I noticed ERA+ does not use this, and actually uses the inverse of this. The ERA+ formula (again, assuming I have the formula correct) is (LgERA/ERA)*100. So if the LgERA is 4.00 and your ERA is 3.00, you get an ERA+ of 133. However, it seems to me that one fourth of 4 is 1, and the ERA+ should actually be 125, or 1.25 times that of league average.

I understand that the formulas will be different, since ERA is an inverted statistic, but isn't there a better way to calculate ERA+?

I was grinding numbers, and I think I found a better formula:

This formula rightly puts LgERA in the denominator, and now factors ERA as a ratio of league average, rather than as a ratio of the player's ERA.

Thoughts? Feelings? Did I mess up somewhere or misunderstand something?

Thanks

AGNP

I've always understood OPS+ to be OPS (technically the sum of its parts) in relation to league average, expressed as XXX% of league average.

In the simplest terms, a player with an .OBP of .300 and a SLG of .600 in a league with an OBP of .250 and a SLG of .400 would have a an OBP+ of 120, a SLG+ of 150 and an OPS+ of 170, assuming my math is correct.

But the accuracy of my math isn't my concern. My concern is that the SLG+ and OBP+ figures are quoted in relation to league average. If your OBP is .300 and the league is at .200, your OBP+ is 150, or 1.5 times that of league average.

However, I noticed ERA+ does not use this, and actually uses the inverse of this. The ERA+ formula (again, assuming I have the formula correct) is (LgERA/ERA)*100. So if the LgERA is 4.00 and your ERA is 3.00, you get an ERA+ of 133. However, it seems to me that one fourth of 4 is 1, and the ERA+ should actually be 125, or 1.25 times that of league average.

I understand that the formulas will be different, since ERA is an inverted statistic, but isn't there a better way to calculate ERA+?

I was grinding numbers, and I think I found a better formula:

**((LgERA-ERA)/LgERA)+1)*100**This formula rightly puts LgERA in the denominator, and now factors ERA as a ratio of league average, rather than as a ratio of the player's ERA.

Thoughts? Feelings? Did I mess up somewhere or misunderstand something?

Thanks

AGNP

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