Z-Bo can barely jump an inch off the ground, that's why he doesn't get blocks. And
Bosh may not be a great defender, but he's far better than Blake is. Bosh played great defense during the NBA finals. Bosh is a decent passer, he gets the job done. Bosh is much more versatile scoring in comparison to Blake, obviously Blake is still young and unpolished, but Bosh is a great shooter and can get to the rim surprisingly well at times too. In the 14 games Wade missed this season, Bosh averaged around 25 PPG as LBJ's 2nd option. He's definitely a better scorer than Blake is.