A few days ago a reader posed this question to me:
@bjmfiedler good idea for a blog post. i'll address it tomorrow.
— Tania Ganguli (@taniaganguli) January 20, 2014
It's a reasonable thing to ask, and I promised an answer in a blog post. (As an aside, I'll do this more frequently during the offseason. Thoughtful questions that require more than 140-character responses might get posts.)
When Texans owner Bob McNair fired former head coach Gary Kubiak, part of his decision was influenced by Kubiak's seeming indecision with his quarterbacks.
The night before being fired, Kubiak had pulled Keenum from the Texans' loss in Jacksonville to try and win with Matt Schaub. It was the second time Kubiak had pulled Keenum during a game after declaring the first-year player his starter. Keenum had struggled in both of those games and wasn't seeming to get better, but Kubiak's waffling only seemed to make things worse. Upon firing Kubiak, McNair declared that Wade Phillips would be interim head coach and Keenum would start the rest of the season.
"We need to find out whether Case is capable of being a starter or whether he's capable of being a backup," McNair said that day. "And the way you find that out is by playing him."
What McNair saw in the next game, before a thumb injury ended his season, was a quarterback who had trouble adjusting to pressure and who tried to use his legs to get out of trouble far too often. Sure, when his improvisation succeeded the results were impressive, but those times were the exception. It wasn't that Keenum didn't know what to do. Both he and Phillips said he did. Keenum just didn't react in the ways he knew he should. He made the wrong decision repeatedly.
In my post about the Texans' offensive line, I noted that Keenum averaged about 3.7 seconds from snap to sack, which is a decent amount of time. One commenter suggested that time was because Keenum bought time for himself while under pressure. The problem is, if you're buying time and then getting sacked anyway, that's not good either. It's part of why he led the NFL in yards lost per sack last season, losing an average of 10.58 yards per sack.
Maybe Keenum stopped trusting himself. Maybe with the right coaches and a competition, he'll recover and improve. Sometimes a quarterback improves later in his career, though few are given the chance for that kind of growth these days.
The problem is you don't know. He's not there yet, at the point where he has established himself as a capable starting NFL quarterback. Sure, there would be unknowns with a drafted rookie, too. But in that case, the same thing that worked for Keenum in October could go against him now. The less a quarterback has had a chance to show, the greater his potential upside.