Nowhere to run
A combination of rugged 49ers defense and a poor start doomed Tampa Bay’s ground game, which has been erratic in the past month. The Bucs had 39 yards rushing on 12 attempts against the 49ers.

Bobby Rainey, who set the early tone in last week’s win against Buffalo by dashing 80 yards for a score on the second snap of the game, carried 11 times for 27 yards against San Francisco. And with the 49ers ahead 17-0 before halftime, Tampa Bay ran the ball only three times in the final two quarters.

“Getting out there on those first couple of drives and shutting them down, that gave us our rhythm and flow and kind of set us up for the whole game,’’ said 49ers defensive end Aldon Smith, who posted two of San Francisco’s four sacks, adding two tackles for loss and three QB hits.

For the third time in four games, the Bucs failed to rush for more than 66 yards. And in the past five seasons, they are 1-17 when they run the ball 20 times or fewer. “Today, we weren’t effective running the football,’’ Bucs coach Greg Schiano said. “We’re playing some really good defenses, but that’s what you’re going to see in the NFL. We have to get better. We’re just not performing at a consistent enough level. It’s not from a lack of effort or a lack of work — these guys are laying it on the line, coaches and players alike. We’re just not getting the results we want all the time.’’

After a 27-6 loss at Carolina on Dec. 1, Tampa Bay defenders lamented their inability to finish off plays with a secure tackle. That issue frequently allowed the Panthers to turn short gains into key first downs and the same problem was evident from the start of Sunday’s 33-14 setback. “That was our worst tackling game since Carolina,’’ said rookie cornerback Johnthan Banks, who failed to wrap up quarterback Colin Kaepernick on an early third down, leading to a 17-yard scramble and an eventual touchdown. “We’ve got to do better.’’

In the second quarter, with the 49ers facing a third-and-15 from midfield, wide receiver Anquan Boldin spun out of the grasp of cornerback Darrelle Revis for a 25-yard gain, setting up a Phil Dawson field goal and a 10-0 advantage. “I think we did a good job overall, but we just missed some tackles,’’ said linebacker Lavonte David, who was credited with 10 stops. “We had (Kaepernick) a bunch of times and we let him get away.’’