I don't think this ends well - but I hope like hell I am wrong.
What he might have better than Schaub? A slightly better arm, and slightly better mobility (damning with faint praise). Might be a harder "take down" by a rusher as he is built better and is a bit more athletic. I like his release point a bit better - more overhanded than Matt S more sidearmed delivery - so potentially fewer batter balls.
Worse? To me, mentally Matt S is light years ahead of Matt L. Leinart never really seems to know where he is going with the ball, and the guy has to be wide open or he won't throw it....making him a statue back there. You think Schaub holds the ball too long...just wait! He is indesive as hell. Sacks are fixing to go up - way up imo. He also seems to rarely test the secondary deep, or even in the medium range. How many balls has he thrown here beyond 10-15 yards...and that is pushing it. It's ALL dink and dunk.
His accuracy is lousy. Schaub has been medicore this year in his accuracy, probably his worst year - but Leinert would be extremely lucky to be anywhere near as accurate as Schaub at his worst. Not exactly what you are looking for.
He has a long windup and a very slow release. He is so indecisve I don't see where it matters about his better arm slot and he just has this long wind up like he is Nolan Ryan. Interceptions are fixing to go way up, leading to higher scores by the opposition as the D will be put into way more bad spots due to turnovers and increased punting.
Schaub has total command of the offense and just has it together between his ears. When the ball is snapped, Schaub knows exactly where he wants to go, goes thru his progressions, "Generally" doesn't make bone-headed throws (yes he makes some like all QB's not named the top 3) has learned to protect the ball better, and is willing to throw it into the cheap seats instead of throwing a pick. Leinart as a QB is just dumb. Sorry, he is. Might be a smart person, but his football/QB IQ is borderline retarded.
If I was a student assigned a homework assignment to draw up the charastericstics of a great QB, and I turned in Schaub and Leinart as my report to turn in, I would get a B turning in my Schaub homework, and a D+ turning in my Leinart homework.
I wish I could be more postive. I'm trying hard. But I just don't see it myself. If the Texans are to go anywhere, Leinart has to be our Trent Dilfer - in other words, just get out of the way and don't screw up and make things worse. If he does that, we have a fighting chance. If he is a screw-up, we have zero chance of doing anything.