At the end of the game, if the other team is one or two points ahead, a team goes to its best isolation player. Often, they will clear one side of the floor and let the clock run to 5 seconds. Having a good isolation player is crucial to being a good team. Here's who you want in isolation plays in general and, especially, at the end of games.
10. Lebron James
Surprised to see him so far down this list? If you saw him try to catch the Heat up with an untimely 3 point shot that hit off the very top of the backboard, or any other unsightly jump shots, you would understand. Isolation players do not need to be able to nail 3s, there is usually some other player on the team for this role (in Miami's case, Mike Miller.)
They do need to do 4 things well: get to the rim, get fouled, hit free throws once they are fouled and hit midrange jumps shots. Lebron scores an A+ on the first two, a B on hitting free throws and an unfortunate C - when it comes to hitting jump shots. This is not going to put you at the top of this list.
9. Dwayne Wade
Dwayne Wade has the same problem Lebron does: he is unable to hit midrange jumpers. If the Heat are able to keep Bosh in good health, then this should not hurt them that much. Quite ironically, despite being the worse (or really the least best) of the Heat Big Three, Bosh is more crucial to have on the floor because he fills such a different role than Lebron and Wade. Wade gets the nod here because he is slightly better around the basket, as well as a slightly better midrange shooter, though he is about the same on shooting free throws and getting fouled as Lebron.
Amar'e may not be the best in the NBA like Wade and Lebron are at getting to the rim and getting fouled (they are one and two, respectively.) He is someone you cannot lay off in the midrange and just bring a center up to plug the middle when he drives. Your perimeter defender has to play further up on Amar'e because of his midrange, and he has the ability to get by this defender and pull up for a 12 to 15 footer before the center can come. He can also kill you if his team is able to get the ball into the post (something Wade and Lebron can't do.)
Rudy Gay can score every which way from any place on the floor. He has always been good at creating shots and now he is deadly accurate with them. There are two reasons he is not higher on this list: 1. he does not get to the line too often and 2. he has not have as big a body of work as these other players. Expect him to pass every player on this list short of Durant in the next couple years.
I tried to stay away from considering passing in this category, especially because most of the emphasis is how the player would do with the ball in his hand at the end of the game. With Rose, however, it is impossible to separate how he passes from how he is defended at the end of the game.
He is not as efficient as any of the other players on this list (save for the fact that he is turning into a better 3 point shooter than some of these other guys.) The problem defending him in isolation at the end of the game is that you cannot bring a help defender because of the pass and you cannot play up on him because he will blow by you. Teams are doing what they have done for the past couple years: giving him space for the midrange when he is in isolation.
Unfortunately for his opponents, this has just forced him to work on his midrange and gain experience with it. He is still only a little above average, but he is improving, and I expect him to slide into 3 place on this list behind Gay and Durant in the next couple years.
5. Dirk Nowitzki
Nowitzki, like the next 3 players on this list, probably only has a year more near the top because of his age. That said, Nowitzki is the only other player than Amar'e on this list that has a good enough dribble to isolate at the top of the key and good enough post game to go to on the block. Age is catching up with him, but age usually has little effect on shooting touch. While he can no longer blow past most power forwards, he is still nifty with ball fakes and creating and hitting a shot from anywhere.
4. Paul Pierce
Pierce never relied on speed to get his shot off, and because of this age has not affected him as it might most. Instead, he either powers through defenders or uses a number of ball fakes to get himself his shot AND get to the free throw line (only Kobe is better at this.) He is especially effective at the end of games because he has a "sweet spot" probably better than any other player's sweet spot in the game (around the top of key, in or just outside the right side of the circle.)
Melo is not nearly as efficient as the other players on this list (save for his midrange compared to Lebron and Wade.) The reason he makes it here is because he has been going it basically alone in isolation on his team. Because of this, he has become the best in the NBA at getting off a shot. This is partly the reason he is less efficient. He often has to bail his team out at the end of possessions, something these other players (even Gay because of Mayo) do not have to do.
The only surprise here is that he is no longer at number 1. He may not put up the same numbers as he used to, but he is the same player. He can get to the basket and finish, get fouled and get to the free throw line, hit a midrange in isolation, pull up off the dribble, fadeaway, etc., etc. The point is, if you had to choose one person at the end of a game to take a shot, you would choose him unless...
You could choose Kevin Durant. The only part of his scoring repertoire which is not better than Kobe's is his fadeaways (Kobe still retains the title for best fadeaways in the game.) He is just lethal off the dribble and even in spot up places. His arms are freakishly long and he is very tall (he is listed at 6'9, but seeing him on the floor it is difficult to imagine he is anything less than 6'11.) He can get a shot over anyone, anywhere at any time. And he will hit them like he was wide open when he took it.