What Hand did Teddy KGB have at the end of Rounders

[pstripling]

Perhaps this is a good question, perhaps not. My mother actually posed this question to me over the Christmas holiday. We were watching Rounders and after the final hand she turned to me and said "What did the bad guy have?"

I didn't really know what to say, to my embarrassment I hadn't really thought about it up until now.

As a refresher heres how the hand played out

Matt Damon (MD) and Teddy KGB, Heads up, no limit HE. Blinds 50/100. MD has KGB slightly outchipped but both are right around 30,000.

Preflop

MD (8 [img]/images/graemlins/spade.gif[/img] 9 [img]/images/graemlins/spade.gif[/img]) raises to 200, KGB calls

Pot 400
Flop: 6 [img]/images/graemlins/diamond.gif[/img] 7 [img]/images/graemlins/spade.gif[/img] T [img]/images/graemlins/heart.gif[/img]

MD checks, KGB bets 2000, MD calls

Pot 4,400
Turn: 2 [img]/images/graemlins/club.gif[/img]

MD checks, KGB bets pot 4,400, MD calls

Pot 13,200
River: A [img]/images/graemlins/spade.gif[/img]

MD checks, KGB all in, MD calls

Okay, so we know that MD wins and goes off to test his skill in Vegas. KGB goes into his cruddy little back room to munch Oreos. What do you think KGB had?

My first thought was a set of sixes or sevens. The overbet on the flop looks wrong for that though. 2 Pair was my next guess, but going all in when the ace hits the river is terrible with 2 smaller pair as MD could have had A7 or the like.

The hand I keep coming up with for KGB to have is AA. He likes to slowplay those, as we saw in the first confrontation between him and MD...so no preflop raise from him. The overbet on the flop looks strange here, but I guess it is meant to fold a hand like 87 or 9T. Every street except for the river it seems as if he is trying to milk MD if he is ahead, but is not committing all of his chips. When the ace hits the river, the only hand that beats him is the straight.

Of course he might have had 23os and been completely on tilt...but judging by his reaction when MD shows the straight I think he had a pretty good hand that got cracked.

I will say that I hardly ever play NL. I'm mostly a limit player and don't have nearly the grasp of NL that I would like to have. Basically, I'm saying that due to my lack of experience I could be way off here. I would love to here from some of those with more experience.

So what do you think he had, and why?