1. As said before, batted balls aren't even a big deal relative to how many balls are thrown, so it shouldn't even be a factor.
Derek Anderson had 6% of his passed batted down. Brees had 3%. Of course that's significant. And the thing is, Brees has adopted a bunch of aspects into his game to lower his batted-down rate, and he's still near the top of the league. a 6 foot guy with replacement-level NFL talent would likely get a ton of passes batted down.
Height shouldn't be a factor for drafting a QB; if batted balls are an issue, it would show up during that player's college production.
defensive linemen and linebackers are MUCH taller, faster, and more athletic in the NFL than in college.
And Warner is 6'2. He's halfway between Brees and Brady, and the conventional wisdom says that 6'1 is the cutoff point. I'm certainly open to the idea that the conventional wisdom is wrong (as it often is), but you're taking it much, much further than that...
2. The entire field of picking guys simply based on his height, 40-time, or vertical is not only lazy but also completely flawed. You don't even have to look at Jerry Rice, look at Greg Jennings or other receivers in the game today who can play football but can't run a 40 in shorts the fastest (who cares).
Nobody's arguing otherwise. height, speed, and jumping ability don't guarantee success or failure. Plenty of blue-chip athletes fail, and plenty of subpar athletes succeed. Does that mean that speed, height, and athleticism don't matter? Of course it doesn't- it just means that they're several of many very important factors in determining success.
Excellent players can succeed in spite of their physical shortcomings, but that doesn't make them irrelevant. So because Vince Young succeeds despite having the IQ of a brick, intelligence doesn't matter. Because Chad Pennington succeeds despite having a weak arm, arm strength doesn't matter. Because Brett Favre succeeds despite throwing a bunch of INTs, decisionmaking doesn't matter. Because Brady succeeds despite being immobile, mobility doesn't matter. Because Ben Roethlisberger succeeds despite poor pocket presence, pocket presence doesn't matter. Therefore, we must conclude that none of these things matter in terms of determining what makes a good QB.
...do you see how flawed this is?
The height rule/guide is ridiculous in the first place. There are tons of players who don't fit the guides, and they aren't the exception, the rules in the first place aren't even related to success.
They're not? Because sure, you can name a couple excellent QBs who are under 6'2. But I can name a ton of great QBs who are over 6'2.
Bill Walsh, one of the best drafters in history, didn't give a crap about measurables. He would bring in a player and actually see how they performed in his drills and plays.
He cared more about a player's intelligence, work ethic, talent and feel for the game than athleticism. That's hardly earth-shattering. Once again, nobody's claiming that athleticism determines success. Just that it's one of several important factors to consider, alongside intelligence, work ethic, and talent.