Let me hit a few issues here
Davis has not been healthy since being in the pros. Had several injuires last year and always has a nagging this or that. For that reason alone he can't be the focus of the offense.
That said, Davis attempts to play through the injuries, but honestly he has too many. The reason he is not explosive is that he is not healthy, and unfortunately a year and half in I don't think he will ever be.
As for the draft, the only position that i am ruling out as first round material is QB. While DL seems the most glaring need, i expect that the Texans will be in a good position to go BPA and be able to justify taking any position where there is a potential "difference maker"