SANTA CLARA --- The 49ers have taken the vaunted Eagles offense out of the game and yet still trail 21-13 at the half.
That's due to two huge special teams blunders and a Colin Kaepernick interception that was returned for a touchdown. Those miscues have more than outweighed the 49ers' defensive performance as well as Frank Gore's big half for the 49ers.
A week after they allowed a blocked field goal, the 49ers opened the game by allowing a blocked punt from their own end zone. Eagles tight end Trey Burton end simply bull-rushed Dan Skuta on the play and backed him up far enough to smother Andy Lee's punt.
The coverage units, which are without last year's veterans Ray Ventrone and C.J. Spillman, also lapsed in the second quarter when Darren Sproles took a punt 82 yards up the sideline for a touchdown. That score occurred one series after Kaepernick, tracking Brandon Lloyd on a crossing route, failed to see Malcolm Jenkins lurking in the middle.
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The Eagles safety intercepted the pass, then broke three 49ers tackles – including one by Kaepernick – on his way to a 53-yard touchdown.
Those mistakes erased a strong half by San Francisco's defense, which has held quarterback Nick Foles, the only passer in the league with three, 300-plus yard games entering the weekend, to just 92 yards and five first downs. Running backs Darren Sproles and LeSean McCoy have combined for six rushing yards.
The 49ers began the game with multiple wide receivers and without a fullback. But over the course of the half, they reverted to their familiar ground-and-pound approach. Gore in particular responded. He has 10 carries for 59 yards a week after rushing six times for 10 yards.
Right tackle Anthony Davis, making his first start of the season, was knocked out of the game with an apparent knee injury. On the play Eagles defender Brandon Graham beat left tackle Joe Staley, sacked Kaepernick and then both quarterback and Graham crashed into the back of Davis' knee.
Davis walked off the field to the 49ers locker room and has not returned. Jonathan Martin, who started the team's first three games, has replaced him at right tackle.
On the ensuing play, Kaepernick was flushed to his left. But he kept his eyes up and spotted Gore on the opposite side of the field. His pass went 30 yards laterally, Gore caught it, stiff-armed a defender and ran 55 yards for his first touchdown catch since midway through the 2012 season.
Receiver Michael Crabtree also was injured. It came on a short, first-quarter reception, and he spent the next two series on the sideline with medical personnel looking at his left foot. Crabtree has had a series of foot and lower leg injuries since his final year at Texas Tech. He later returned to the field and had a short reception at the end of the second quarter.
Penalties continue to be an issue for San Francisco.
They've been flagged seven times for 60 yards as opposed to five penalties for 32 yards by the Eagles. Ed Hochuli's crew, which averages 19.5 penalties a game, has called 12 so far.
Read Matt Barrows’ blogs and archives at www.sacbee.com/sf49ers .