I do think that some of Locksley's problems were his own. I think his decision making under pressure was very suspect. Of course he was under pressure like 95% of plays because of Dimel's incompetence.
I really do feel like as bad as our D was, they were good enough for a team with an acceptable offense to win 5-6 games.
Reasonably, the QB was maybe 10-20% of the offensive problems, and Dimel & co were the remainder. Mahomes might have gotten us 2 more wins, but the coaches would have given away the rest.