Does anyone open push the flop? This would be about 3x the pot, so it's not an absurd overbet. It kind of screams flush draw, but with the middle pair, Hero doesn't hate a call from a naked A. Check-raising risks pricing a lot of hands, including Villain's, into a call. Villain found a call with just a draw here, and that was after a cowardly bet; if he had bet 1/2-2/3 of the pot, it's even more unlikely he'd fold to a check-raise all-in. Even calling with A and a weak kicker could be a tough decision for some, though probably not for the CO, given his stack.