I wouldn't really worry about how he's done in other places as much as you may, considering that our system has basically been in place for awhile, and he has a much better grouping of talent and coaching here.
Brady and Belichick go a long way towards making up the difference in my opinion.
On top of that if Belichick doesn't care for Daboll or has any doubts, he simply won't make him OC. I would imagine that we'd be able to switch some things up in terms of adjustments coming from BB himself should we get off to a bad start next year. As I said though, I'm still not convinced that McDaniels will definitely leave this year.