Well since you asked...where do I begin??
Shaq:
The rule changes pretty much renders his money moves (running over people) useless. When he was younger, he was quicker so he could hook people when he spun to the basket and it wouldn't get called. Now that he is slower, it's more obvious.
Shaq is a perfect example of a robotic player that depends on one move. think Mike Tyson in his prime. Mike's fundamentals eroded to the point that if he was forced to actually box, he would get beaten. But he always had that knock out power which made him dangerous. Shaq is the same way. he has no jumper, no finesse moves, so he has nothing to fall back on. Zo has been getting equal if not more playing time with him in foul trouble..but the Heat offense is not built to have him as the focal point.
Lack of young athletic talent:
I thought Kenny Smith did an excellent job or covering this point. They have no perimeter defender, and no player that can run on the fast break. They have failed to infuse any young talent into their team.
Lack of rebounding:
The Heat consistently get killed on the boards. The opposing team is getting to the loose balls faster than the Heat.
Dwayne Wade:
The injury issue does NOT exempt him from having poor decision making ability and poor shot selection.
Small Forward:
Eddie Jones, Antoine Walker and James Posey are missed severely for what they offer. Jones is an above average perimeter defender and a solid three point shooter at this stage in his career and Posey is an athletic defender. They made an attempt to replace them with Penny Hardaway and Ricky Davis. Penny is hurt, and Davis just doesn't fit with the team needs. Which brings me to..
Lack of bench players:
There are no real serviceable plaeyrs off the bench once you get past Zo and Ricky Davis. And finally..
Lack of caring:
The Heat lack that commitment to basketball. Riley has touched on this several times. If Riley can't motivate his team, then it is his fault, you can't coach effort. If the players don't care, then they won't play well. Look at the Timberwolves. They don't have anywhere near the talent of the Heat, but because they play competitive basketball, they are in every game until the end.
This is my opinion..and I'm sticking to it.