Clutch Changes
Last night we rolled in some changes to the way Clutch is calculated. For the most part, the results remained the same, but there are a few key differences which you should be aware of.
Clutch is no longer calculated using OPS Wins. Instead it’s calculated using WPA/LI, which is WPA divided by LI on a play-by-play basis. Take Alex Rodriguez for example who has a WPA of 1.03 and a pLI of 1.51. His WPA divided by pLI on a full season basis would be .68. Unfortunately, that is weighting each play incorrectly and does not correctly neutralize WPA. When you correctly weight each plate appearance by LI, his WPA/LI is 1.16. To get the new Clutch score, you merely do: WPA – WPA/LI.
Tangotiger goes into the details of what’s going on here in comment #5: What Exactly Clutch Measures.
David Appelman is the creator of FanGraphs.
Even further explanation is in posts 11 and 12 of that same link:
http://www.insidethebook.com/ee/index.php/site/comments/wpa_to_arod_i_love_you/#11
I encourage all to read it. It’s an important concept, and big kudos to David for implementing it.