I agree with a good amount of what was said. I don't know much about the Texans passing game in terms of where the ball was supposed to be thrown or what the 1,2,3 options are...but I do know about playing QB.
Pass plays aren't designed to throw to your best receiver. They are designed to take advantage of the week or open spots in a defense. You read the defense and react to what they do. I'm sure he has missed open receivers, but he's learning and improving IMO. Brett Favre didn't emerge until after he learned and grew into one of the greatest quarterbacks in the history of the NFL...David will learn. It's always safer to check down to a back and pick up a few yards than try something and throw an INT.
As far as depth is concerned, I feel that we improved in that area this offseason and in the draft. Yeah, we still have some work to do but we're getting there. This season will be much better and more enjoyable.