If being a good coach means evaluating talent (and getting it right much of the time - no one is 100%), having the admiration of your players, having the personal charisma to get "buy in," having a broad stable of assistant coach candidates you can call upon, having a loyal set of assistants you can immediately plug in, and having a clear vision of what sort of system you want to run... then it may be the case that Frost is a good coach.
Frost is failing because he wants to run a system predicted upon a dual-threat QB. If the question is: is it the case that a system predicated on a dual-threat QB is effective? The answer is: yes. The trouble is that smuggled into that question is a second one: can you actually land a dual-threat QB? Or can you only land a running back who can throw the ball a little?
There are between 0 and 2 true dual-threat QB's throughout the nation on any given year. That is why this is a terrible plan. Frost can't get the piece he needs. If he could, he'd succeed.
And to make matters worse, he can't reverse course over night. The entire offense is built around the concept that he'll have a dual-threat QB. So if he does the right thing and reverses course, you need to give him about 3 more years to finish the project of building a different kind of offense. But, then again, you'd need to give the next guy that.