Originally Posted by Sean Pilgrim
Well, I'm confused then...
It only calculates an all in EV if you are all in before showdown. Otherwise, it just figures your EV is the same as your actual winnings.
So if we're playing $50NL, and we both have 100bb stacks, and I jam QQ and you jam AKs preflop, then your EV is about -$5, and mine is $5 (because QQ has roughly a 55% chance to win against AKs).
Thus, if you do that 4 times, the QQ hand would be up $20 on average (and thus would have an EV of $20). However, if you lose all four times with QQ, your actual winnings would be -$200. It shows you that you're running bad.
However, there's a ton of other ways to run bad playing NLHE that EV doesn't take into account. So you could actually be running awesome, but be below all-in EV, or vice versa.