re: Are the clock management issues due to

I would put the major blame on Crowton, if it was indeed he who called the substitutions at the end of the game. Miles gets blame for not saying no, or making sure that his OC has a plan to deal with the clock at the end of the game before the game (and a QB prepared to execute it).

Apparently, the coaches expected JJ to score on the next to the last play before the clock meltdown and had no backup plan for a second play, or JJ didn't know/remember what it was. He is standing on the field, looking to the sideline for the call, and all of sudden subs come running onto the field. At that point JJ looks like he has no clue and is just standingg looking bewildered. The major problem was putting in subs at that point without the QB
having any idea of what to do.

It was obviously badly managed by someone, and it is Miles' responsibilty to make sure that it is managed properly, regardless of who actually made the call for the substitutions.