Lets remember too... closing takes time to learn. Its a common thing for young teams like ours, both in individual games as well as playoff series. While Donovan might be in the "Big Brother" role and has experienced the playoffs multiple times, he was also one of the youngest players on that Utah team with multiple craft vets like Mike Conley and Joe Ingles on the team.
I think a lot of the 4th quarter and end of game inconsistency comes as a direct result of our overall lack of experience (from a HC perspective as well!). Also notice that I said "inconsistency" rather than "struggles" because, even though the Cavs have blown multiple close games in the 4th, they're also still 6-0 in overtime, I believe!
The future is still bright... just stay healthy both from a physical and culture standpoint, and the future is crazy-bright!