[Cooker]

Obviously, the person that folded the best hand made the worst mistake. If the SB knew everyone's cards, the best play would have been to reraise the turn to charge the flush draw the most money to see another card. So by the FTOP the person with K5 made the worst play without a doubt.

MP2's play not only isn't terrible, but is probably correct even if he knows both of your hands (Maybe it is a little too fancy for such a small pot though). If either of the other 2 players fold, he goes from a 9 outer to a 12 outer. His play is a classic semibluff, and it appeared to have worked very well. Take into account that he doesn't know what he is up against, after an all check flop, ace high might be the best hand. I think he played the hand very well. Looks like a textbook semibluff to me. He will probably think he caught you on a pure bluff until the day he dies, and it was just bad luck that the button was a calling station that wouldn't release a very weak hand.

I think the button is obviously a calling station, and they get lucky sometimes. There is no point discussing his play, because it is well known that calling stations lose their money eventually. The only reason he won this pot is because the best hand folded to very little pressure. If anything, he played more aggressively than the SB, because he didn't fold.

I think folding top pair with no flush or straight possibilities on the board, and an all check flop is a pretty bad play, even if you don't know his cards. He could easily be raising on the flush semibluff, with second or third pair, almost anything. I might have gone into check call mode (because I struggle a little with my aggresiiveness sometimes), but a fold in that spot is the weakest play anyone makes at the table, and it hurt the most. I actually think not betting top pair on the flop is pretty weak also. Top pair weak kicker is worth a bet on the flop, but probably not strong enough to check raise. Top pair is almost always worth a showdown unless the board gets really scary, or you have strong evidence that you are against a better kicker (like a preflop raise, but you shouldn't have played this hand at all then). The only possible exception to showing down top pair is a really weak ace (A2 or A3), because many people play any Ace, where not that many play any king.

I am not saying that you are a bad player. You may be quite a bit better than me, but I think you clearly played this particular hand in about the worst way possible on every street except possibly preflop.