Excellent question!
Short answer- I haven't incorporated umpires in my play or really even looked into it.
Longer answer- I have thought about looking into it going back to last year. So much so that I posted this question in the "The Bat" thread on RG (The Bat is a projection model for sale at RG)
That was my nice way of saying I'm not interested in what your model thinks hitter X will do vs pitcher Y in Z park, but I might be willing to pay for this if I can separate out the stuff I want (umpires and weather). Turns out you can't btw.
and that's about the extent of my research on the subject. Good topic for an off season project this winter. This would have been huge in the 90's btw, before ump grading they really called a game how they wanted to call a game. I'm guessing it's a lot less drastic now, and probably a bit noisy, thus my lack of urgency. OTOH I'll take any sliver of edge I can get, so yeah, I need to at least look into it.
Tonight was brutal. Worst hitting ever other than a few shares of Kepler in otherwise bad Twin stacks (no Mauer). Anyway hitting was so bad tonight Kepler's 3 bombs alone were enough to cash in most spots, saving me from a possible zero.
Day 121
Buyins $700, Payout $208,
-$492
Season +$29,279
So the Rally was 60K tonight and again tomorrow, which is about what I expected it to be all season. No idea why they waited until Aug to make it a decent GPP again.
I'm really on the fence about reupping at DK for NFL. On the one hand it should help smooth out variance as I can get my volume at slightly lower stakes spread over more entries, plus the difference in rules/pricing allowing a wider range of players.
On the other hand I hate the MM and MM type super top heavy GPP's that DK is so fond of. That's a big reason I left the site over a year ago and afaict it's only gotten worse. Also, playing 1 site allows me to focus in 100% on that set of pricing and rules. No big deal for the spreadsheet/algo guys, but I'm doing everything by hand from out of my head, so less clutter is more, a lot more.