The talent simply isn't there; he's been absolutely terrible this season outside of a handful of games. That unavoidable fact aside, again, it comes back to thinking that if a player could "just" become a completely different player after 20 years in basically the same role and on the same team, then sure, he could become a valuable role player. None of those players did that. This isn't being David Robinson and just cutting your minutes; he would have to become a completely different player, if he were actually even capable of playing usefully consistently. Pointing to guys like Garnett and Pierce and Carter, who changed teams and systems and roles much, much earlier in their careers (sometimes multiple times), just doesn't work.