It's not just tired legs, although I'm willing to accept that as one of the main culprits.
Maybe it's my selective memory, but the shots he takes in the final 5 minutes of the game are not the same shots he takes earlier in the game. We can't expect Kobe (a tired Kobe at that) to get the ball near the 3pt line, make a move, barely get separation from his man, and then make a fallaway. It's just not going to go in all that often. We can't just put him behind the 3pt line, have him hold the ball for 5 seconds, and make magic happen. He can be much more effective making quick moves off the catch from within 15-20 feet. Sometimes, Pau comes to set a pick and he doesn't even use it when good things almost always happens when he does use the pick (like an open jumper by Pau). He can be so much more effective and efficient in other ways.