Jean has experienced a career resurgence in his first year with the Diamondbacks, enough to get an award for such things, in my opinion.
The only piece of criteria I could find for the "Comeback Player of the Year" was "re-emerged on the baseball field during a given season." From that alone, that could mean anything. You could argue that a player who went to the dugout for a pee then came back and made a good play could win it, cause he "re-emerged" in the most literal sense. Also the writer who voted with this logic's house would justifiably be engulfed in rolls of toilet paper.