GLENDALE, Ariz. -- What happened was perfectly natural and understandable, given the experience level of the Houston Texans' starting quarterback. It also showed the Arizona Cardinals' ability to understand and adjust to exactly what would make things difficult on their opponent.
Case Keenum played well in the first half. He completed 15 of 26 passes for 159 yards. On the game's first play he was sacked and fumbled, and Arizona returned it for a touchdown. But he threw touchdowns to Andre Johnson and tight end Ryan Griffin, and his passer rating was 101.3.
Then the Cardinals started sending pressure at Keenum, and they did it furiously. Keenum struggled with their adjustment -- something that has been a pattern for the young quarterback -- and the Texans went on to lose 27-24.
In the first half, the Cardinals sent five or more rushers at Keenum on only 9 of 28 dropbacks, according to ESPN Stats & Information. In the second half, they did so on 14 of 20 dropbacks.
All three of Keenum's sacks came against five or more rushers, and he did well to avoid more. Though his touchdown pass to Griffin came in such a situation, Keenum completed only 6 of 19 passes against five or more rushers. He was off target on 21 percent of those passes, by ESPN Stats & Info's analysis, and averaged just 2.4 yards per attempt.
By contrast, Keenum completed 16 of 24 passes against four or fewer rushers, averaged 6.5 yards per attempt and was off target on only 4 percent of those passes.
This is something the Cardinals like to do, though they usually don't do it at quite the rate they did it in the second half Sunday. They came into the game blitzing on a league-high 52 percent of opponents' dropbacks. It helps to have the talented rushers the Cardinals do, but it's especially fruitful against a team with an inexperienced quarterback and one whose second-string running back has been on an active roster for exactly two games.
Keenum's second-half dropoff isn't exclusive to this game. In the three games he's started for the Texans, Keenum's first-half QBR is an excellent 91.1. His second-half QBR is a paltry 12.2. He is much better in the first half than his predecessor Matt Schaub (32.9 QBR) and much worse after halftime than Schaub (44.1 QBR). (Thanks to Stats & Info's Doug Clawson for looking this up for me.)
That's a ratio the Texans can live with this early in Keenum's career. That first-half number shows a lot of promise.
But it's not a ratio that will work in the long term. Keenum has to improve from here. He can't let opponents' adjustments work so well on him as his career progresses. Successful quarterbacks can outsmart them.