Just by looking at his pass attempts tells absolutely nothing about when he was throwing the ball most (in the second half) and out of what formations he performed better in (pro sets vs spread).
		
		
	 
NFL.com has some really nice situational stat splits on their site. Here is Schaub's breakdown:
Attempts 	Att 	Comp 	Pct 	Yds 	Avg 	Lng 	TD 	Int 	1st 	1st% 	20+ 	Sck 	Rate
Attempts 1-Through-10 	160 	97 	60.6 	1,168 	7.3 	47 	6 	3 	54 	33.8 	20 	0 	87.7
Attempts 11-Through-20 	157 	103 	65.6 	1,205 	7.7 	60 	5 	5 	66 	42.0 	13 	0 	86.1
Attempts 21-Through-30 	141 	101 	71.6 	1,300 	9.2 	50 	8 	0 	64 	45.4 	17 	0 	119.1
Attempts 31+ 	116 	64 	55.2 	697 	6.0 	39 	5 	4 	38 	32.8 	9 	0 	73.1
 
What sticks out to me here is that he puts up his worst numbers in attempts 31+, which supports my notion that the more you trust Schaub with the game the more he will do to fuck you. Though as you said when playing from behind as much as they do there are a lot of other variables to consider.
Here's his margin of victory split:
Point Situation 	Att 	Comp 	Pct 	Yds 	Avg 	Lng 	TD 	Int 	1st 	1st% 	20+ 	Sck 	Rate
Ahead 	90 	64 	71.1 	793 	8.8 	47 	5 	1 	39 	43.3 	16 	6 	111.9
Ahead by 1-8 Points 	51 	38 	74.5 	542 	10.6 	47 	4 	0 	26 	51.0 	13 	4 	134.6
Ahead by 9-16 Points 	33 	22 	66.7 	228 	6.9 	41 	1 	1 	12 	36.4 	3 	2 	83.9
Behind 	381 	242 	63.5 	2,993 	7.9 	60 	17 	10 	153 	40.2 	37 	22 	91.7
Behind by 1-8 Points 	153 	95 	62.1 	1,182 	7.7 	44 	7 	7 	60 	39.2 	16 	9 	82.2
Behind by 9-16 Points 	120 	78 	65.0 	1,012 	8.4 	60 	4 	2 	50 	41.7 	15 	7 	95.6
Tied 	103 	59 	57.3 	584 	5.7 	31 	2 	1 	30 	29.1 	6 	4 	75.9
 
What sticks out to me is that his "behind" stats are pretty nice, but his "behind 1-8" and "tied" numbers are pretty pedestrian. If you ask me, Schaub makes his hay against soft defenses who are protecting a big lead. Once the game tightens back up and things are on the line is when Schaub begins to crack. See the Baltimore game when he led a raging comeback against a bunch of 3-man rushes only to throw the game ending INT in OT. My college roommate is from Houston, a huge Texans fan, and he knows now not to even get his hopes up during a comeback. It's almost as if Schaub is just good enough to almost lead the comeback, but never quite able to complete it. (Anecdotal evidence only goes so far, I know, but if a real Texans fan thinks pretty low of him, something tells me the rest of America should too.) I know part of this is the defense giving up huge plays late in the game, especially the hail mary against the Jaguars, but the numbers don't lie. He plays his worst football when his team is behind by fewer than 8 points or tied. 
This is to say - Schaub is great when playing from way behind, but when trying to take the lead or tie up a close game, Schaub goes back to being average to below average, and more than occasionally, a choke artist.
	
	
		
		
			I watched a lot of the Texans this year and they repeatedly fell behind while running the ball and trying to use playaction to pass and out of pro formations. That is my whole argument here, he is not a good quarterback under center and in 2 WR sets. He excels in spread formations, 3 and 4 WR sets, specifically out of shotgun. And he averaged 7.6ypc, tied for 6th best in the league, and completed 59 passes over 20 yards (2nd in the league) so I don't get why you're trying to label him captain checkdown.
		
		
	 
I forget where I found this stat last year (I promise it wasn't footballoutsiders) and it's a shame NFL.com doesn't list it but of all the top passers, Schaub had the highest percentage of his yardage accumulated after the catch in 2009. The Houston offense calls for a lot of quick hitters that are designed to give the WR space to run. While giving your WR a chance to run after the catch it is definitely a good trait for a QB to have, it also leads to some misleading numbers. 
	
	
		
		
			Playing with one of the worst defenses in the history of the NFL might have had a little to do with his record this year. I'm not saying he is great, I'm saying that the Texans' offense isn't tailored around his strengths.
		
		
	 
His only "strength", in my opinion, is completing slants to the best WR in football. 
	
	
		
		
			I don't believe in this BS that a QB is either a winner or a loser and that's that. It's so silly how a QB is all of a sudden labeled a winner only when the team he is on makes it to the playoffs or wins a super bowl. I believe football is a team sport.
		
		
	 
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			Either way, like I said, I don't believe in labeling a QB a winner or a loser and that's all they are ever going to be.
		
		
	 
This I'll agree with. I think the back to back seasons that have left Nuke with egg on his face have taught us to avoid absolutes when talking about QBs. It's not always black and white in football (in fact it never ever is), and I suppose if Trent Dilfer can win a Super Bowl, even Matt Schaub could given the right situation. "Loser" may be too harsh of a term but I definitely think Schaub is an average QB who puts up impressive stats in meaningless games.