I'll agree that we need another DE, but we need more than one OLB and at least one more decent CB.
As far as Maybin goes, I wonder how motivated he was (or wasn't) in Buffalo. He's in his third(?) year and he's still not playing every down. That's not what I expect from a first-round pick. Also, he wasn't selected by this current regime.
Alright, try this on for size. Houston's best defender is on IR (Mario Williams). Buffalo's best defender is on IR (Kyle Williams). Take those two out of the equation, and which team has more talent on defense? I would say Houston. So, of course, Wade Phillips is going to look better. I think thay Edwards needs more talent, as would any other DC.