I'll give you inconsistent, but only as a result of his injuries. Considering the OL he played behind and lack of good QB play (due to OL or not), I think the success he has had is remarkable. Frankly, I think fragile freddy is the most apt comparison to DD. If you put DD in Taylor's situation (Brunell/JSmith/McCardell to take pressure off, decent OL), I think he puts up the same numbers and same missed time from injuries.
I'm going to disagree with you there. Davis has had some monster games, but he has a surprisingly high number of games in which he averages under 4.0 and 3.0 YPC. His career YPC is significantly lower than Taylor's and he hasn't shown the same kind of ability to make big plays. In three seasons, Davis has only managed one play of 50+ yards. In eight seasons, Taylor has at least 7 plays of 60+ yards.Anyhow, I think you're selling Fred Taylor short. He's getting old, but when he was in his prime he was considered one of the most talented RBs in the league. I don't think anyone (aside from his FF owners) really thinks Domanick Davis is in that same elite class. If you actually look at the other starting RBs around the league, I think you'll find that it's tough to say that DD is any better than average.
In defense of DD, he has suffered from a weak supporting cast, but that team feeds him the rock and designs its gameplans around his abilities.
Anyhow, I still contend that people who think the Texans should pass on Bush because they already have Davis are seriously deluded. In my opinion, it wouldn't be a whole lot different from saying the Bucs should have passed on Cadillac Williams because they had Michael Pittman. Pittman was decent, but Cadillac is that much better. Davis is good, but Bush has a chance to be that much better. Couple that with his name recognition and notoriety, and I think you'll understand why the Texans will almost certainly snag #5 on draft day.