Fair points made all around.
1st, we weren't completely vanilla defensively; we ran some stunts, played some different coverages, etc. However, we didn't really put in full prep or a complete game-plan for Mo State. We could've put in some things to take away their strengths, but we really didn't do that, we simply made due with what we have in, probably much of it prep for better opponents like Miami (and Miami runs a completely different scheme than Mo State). So I'm not super concerned with the coverages.
2nd, Mo State's offense did get the ball out quick. Its valid to say despite the number of pass attempts, its difficult to get sacks. Throw in we didn't really put in a bunch of coverages to defend against their strengths, and you aren't going to get coverage sacks.
All that said, its disappointing not only to not get sacks (or TFLs), but we also didn't get a lot of pressure/hits on the Mo State QBs. I don't think its a huge concern, but its valid to be a bit concerned by the defense in this game. The defensive line will be the key for this defense to be decent, or at least good enough to win. There is no reason to panic, but there is also no reason to believe this defense will be a lot better than last year. To equal last year's success on the field we probably need that to happen, and based on Mo State there is no reason to believe we're a lot better on defense at this point.