How about his whole game is based on his athleticism and he's torn up both of his knees in the past two seasons? :x
This. It's not like Rose was a great all around player. His game was 90%+ based on his athleticism. He hasn't been able to get back on the court for a full season and you assume he's going to be the same guy when he comes back.
At least in Kobe's case he has a much more well rounded game that should allow him to be effective when he comes back, he's not relied solely on his athleticism since the mid early 2000s, he's always had other ways to score and be effective. B. Roy was the same way. D. Rose hasn't proven to be that player yet.