Fatigue.
We showed we could beat Miami during the regular season when the older guys were fresher, but over the course of the entire season they just played too many minutes: Ray (36), Paul (35), Kevin (30).
In the playoffs their minutes increased: Ray (40), Paul (38), Kevin (36).
Young guys and guys in their prime can maintain their energy while playing big minutes, but asking the older guys to do it is doomed to failure.