49ers' defense rested and healthy

By this point on an NFL schedule, no one is entirely healthy. But Bowman noted the 49ers training room this season has far fewer defensive players than in 2012, one reason he sees the stars aligning for San Francisco as the playoffs approach.

"For the most part, we're healthy, man, and I think that's the big thing," Bowman said. "We know we can play, we know can stop offenses and running backs and things like that. My big thing now is that we'??re healthy at the end the month of December and we're able to play at 100 percent level and give it all that we have and not really have any excuses."

Justin Smith, the senior member of the defense, also may be fresher than in previous seasons. He's the only player on the team who is afforded a day off from practice each week.

"Well, he has an injury or two that he'??s nursing, and he's 34 years old. And he's earned that," defensive coordinator Vic Fangio said. "The way he plays on Sunday, it has no negative effect on him. So it's good to do."

Smith's snap count is lower this season as well. In 2011, he averaged 61 snaps a game. Before last year'??s injury, he was averaging 60 snaps. This season, the number is 53. A savings of seven snaps a game doesn'??t seem like much, but over the course of a full season, it amounts to 112 snaps, or two full games' worth of plays.

One reason the 49ers can afford to take Smith out of the game is the emergence of Tony Jerod-Eddie, an undrafted second-year player. He filled in at left defensive end when Ray McDonald was dealing with an ankle injury this month. He has averaged 18 snaps a game in relief since McDonald has been back.

Jerod-Eddie substitutes for Smith and McDonald. He also can play nose tackle, which he did when Glenn Dorsey briefly left Sunday's game against Tampa Bay in the first quarter.

Said Fangio of Jerod-Eddie: "He threw himself right in there, and he??s developed from an undrafted free agent who was on the bubble of making the team or not making the team this year, and now he's developed into a solid backup for us."

At outside linebacker, Dan Skuta and rookie Corey Lemonier have been giving starters Brooks and Aldon Smith a few plays off this season. Last season, the 49ers had next to no depth at the position.

All of which gives the 49ers' defense reason to think it is in good shape - better than last season, even -?? to make a run through the playoffs.

Said safety Donte Whitner: "Healthy and hungry. And hopefully, that equals a Super Bowl."