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Old 01-11-2019, 11:20 AM
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AGuinness AGuinness is offline
Garth Guibord
Join Date: Jan 2016
Location: Portland, OR
Posts: 643

Originally Posted by nat View Post
ERA+ together with innings pitched is probably good enough.

Whether to pay attention to WPA depends on what you want. If you want to know how skilled a pitcher is then WPA just introduces noise that you don't want. A pitcher who gives up a meatball with the bases empty is just as bad of a pitcher as one who gives up a meatball with the bases loaded. If you want to tell the story of a team, or a player, or a pennant race, then it's useful, because it'll tell you who swung the odds the most (even if there was a lot of randomness involved).

(ERA+ takes ERA, adjusts it for the park in which the player was pitching, and compares it to league average, which is automatically set at 100. Higher is better. The normalizations allow for cross-era comparisons.)
ERA+, in my opinion, would not be the best stat for reliever-to-reliever comparisons, since ERA+ would offer a baseline that includes all pitchers in the league.

I think what you describe as "noise" can be helpful for reliever-to-reliever comparisons, because the better relievers would be put into situations where there is higher leverage and by succeeding, accumulate more WPA. (WPA, in my opinion, wouldn't be very useful for starter-to-reliever comparisons)

Either way, ERA- would be better than ERA+, since the former describes the difference between the pitcher to the rest of his league, while the latter describes the difference between the rest of the league to the pitcher. Anyone who isn't SABR-minded, disregard, but here's the explanation:

And I hope Jack Morris supporters don't read the bit about serving up meatballs with bases empty versus bases loaded, it might not sit well with the "pitch to the score" narrative about him... ;P
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