if only the coaching staff will give him enough playing time, he can give more help the team to win.
It won't happen. Instead of giving him enough playing time, why not give that playing time instead to a caliber player?
He's fit in the supporting role, not as a part of the main cast. He can be a valuable backup.
There are times that he played more minutes during the last playoffs, and he was making good minutes. What I'm thinking is, how about giving him more playing time to build more confidence, maybe he is not anymore in his prime but with his experience and his aggressiveness inside, he sure can be a huge asset to the team.
Another reason why he is given limited playing time is, it was the health recommendation after being in a major injury.
I think over time that injury will heal and he will be fully healthy again. Derrick Rose was once seriously injured but when he played in the Knicks, the coaching staff trusted him and he played heavy minutes.