Couple of nice posts from logGrad here and in his follow-up.
AK is a classic "tweener" in the NBA. He doesn't have the skills or shooting ability to play SF and he's just not big enough to withstand the pounding in the NBA at PF. The CBA is full of 6'5" PF's and 6'2" SG's who put up amazing stats every night. And it's the same with Euro ball. AK is a "big" forward in his league. He's got the talent to get rebounds, block some shots and utilize his crazy drive to the hoop. In the NBA, he gets exposed when play gets a little physical. He can't afford to play off his man because EVERY team has FIVE guys who can hit shots (well, nearly every team). I was so tired of seeing AK sag back and the opposing SF hit jump shot after jump shot, or play up and get taken off the dribble. AK has a good game and physique to be successful in Euro ball. As for the NBA, he's lost a step and an inch or so of jumping ability. And that was what made him a rising star 8 years ago. His time is now past as anything but an overpriced role player.
AK doesn't have the skills? He definitely has enough skills to be a SF. His shooting was bad, but he wasn't a god awful shooter. He was a perfectly fine SF. He was just in a system that effectively minimized all of his natural talents. His best position was definitely PF, but I wouldn't go as far as to call him a tweener because he was perfectly capable of playing either position at a high level.