I'm of the mind that we should move up and get our QB, so I absolutely would not take a defender in round 1. If all three QBs are off the board--which is very likely IMO--I'd be looking at Treadwell, Doctson, and Thomas as well as a possible trade down. Treadwell I would take there at 15 regardless of what he runs in the 40. Doctson and Thomas to differing degrees I would need to see their 40 times in order to stack them against the glob of defenders that will be all over our board when pick 15 is up. If Treadwell is gone and Doctson and Thomas don't run well? That would suck, and I'd trade down.
Re: Thomas in particular... IF he runs well he could end up grading better than Treadwell on some boards. I think it's possible. Doctson meanwhile should run well, but his light build does make it necessary to cement him in that 15 range.
In the event a trade down for offensive value is what happens? Well, there should be no shortage of options with guys like QB Cook, as well as one of the aforementioned WRs not to mention guys like Boyd or even the TE Henry.