But now, with his 29th birthday approaching next week, Jennings can't stay on the field. Of the last three games that he's played, he hasn't been able to finish even one.
Jennings suffered a sprained medial collateral knee ligament in mid-December against Oakland and sat out three games. He returned for the playoff game against the Giants but then was able to play just two of the final 23 snaps because of a rib injury.
Less than a week into training camp, Jennings experienced headaches after taking a hit in practice, had to leave the intrasquad scrimmage two days later after absorbing another blow and sat out the next 2½ weeks with a concussion. It was the second concussion of his career; the first came against Arizona in August 2009
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Jennings didn't seem comfortable in close quarters ducking the 49ers' headhunting collection of inside linebackers and safeties.