Quick summary: I'm trying to predict future team performance and I was using wOBA (The formula at http://www.insidethebook.com/woba.shtml ). However, when comparing the OPS/run totals to OPS/run totals that actually have occurred, my run totals were way higher. For instance, the one I have up right now is a .764 OPS. Teams generally scored between 770-800 runs with that OPS. wOBA said they would finish with 827 runs, quite a bit higher than what past results have said.
I have a friend who basically only uses Extrapolated Runs so I decided to try that out. Same results, 827 runs. Except I had excluded GIDP from XR since I didn't project them (wasn't needed for wOBA after all). Well, once I gave the team the average amount of GIDP (~130), that lowered their XR down to 779, a hell of a lot more reasonable number.
So given that XR and wOBA had the same results without GIDP, and that XR then had reasonable results after including GIDP, the easy conclusion is that the issue with wOBA was GIDP.
Is there a wOBA formula that takes GIDP into account? On Fangraphs I believe I've read their wOBA takes base running into account but they've never actually said how. On your power rankings you use BP's base running, but I believe that doesn't take into account GIDP either.
So, yeah, what's up?