Planning to spend part of your Christmas Eve watching the 49ers play the Seahawks in Seattle? Don't just pay attention to what the 49ers are doing.

Also pay attention to what they are not doing.

It has largely escaped notice, thanks to all the other surprising elements of their 2011 success. But unlike other NFL teams, who have had trouble adjusting to the league's new crackdown on head-to-head contact, the 49ers' defenders have almost scrupulously avoided taking any such penalties. Especially in the second half of this season.

That's been smart. But it hasn't been easy. These are men who, ever since donning equipment, have been rewarded for hitting opponents as hard as possible and making their teeth rattle. They haven't had to be too particular about where the contact happens -- until now.

"It's been tough to adjust," 49ers safety Donte Whitner admitted this week. "I do think it's affecting the game. And in a negative way, as far as taking some excitement out of things, the excitement of some of those big hits."

Some of those big and nasty hits, of course, have led to big and terrible concussions. Which is why the NFL has become more of a concussion cop. Whitner understands that part, too. He's never wanted to damage any other player's brain. But the instincts ... well, the instincts are still there. And he is really fighting them.

You can see Whitner's 49ers teammates fighting them, too. Monday night against Pittsburgh, you could almost see safety Dashon Goldson pause and take half a beat to recalibrate his trajectory on one open-field tackle against a Steelers receiver.

Whitner also recalled a specific play at Arizona this month when he confronted Cardinals wide receiver Larry Fitzgerald, who was held up and entangled with another 49ers defender. Whitner had a chance to come in and clean up on Fitzgerald with a huge hit -- above the chest or below. Whitner chose below. He also wonders, with a trace of regret, if he might have held back a bit on the blow.

He should have no regret. His non-action was admirable. And not simply for the sake of Fitzgerald's health.

Here's why: As the playoffs approach, with each play becoming more meaningful, one illegal hit and subsequent penalty could make the difference between a loss and a victory. If the illegal hit leads to a suspension and a missed game, as it did for the Steelers' James Harrison this month, the ramifications could be even more significant.

It is impressive, then, that after one or two flags for helmet-to-helmet contact early in the season, the 49ers have managed to largely stay away from those penalties -- while still stifling opponents and allowing the fewest points in the league.

In doing such, the 49ers could be teaching a lesson to the entire sport. Playing vicious football is possible without playing brain-damage football. Coach Jim Harbaugh credited the players for performing some adjustments on their own but also admitted that his staff has been stressing avoidance of head crashing.

"There's a strike zone," Harbaugh said. "You coach that. Whether it's the quarterback in the pocket or a defenseless player like a receiver ... there are rules, there are techniques. You hit with your shoulder pad, not lead with your helmet in those types of situations."

Vic Fangio, the 49ers' defensive coordinator, has particularly urged his pass rushers to use caution when sacking a quarterback, in terms of keeping the "Target Zone" away from the skull area.

This doesn't mean the 49ers are nonaggressive or fail to push the edge. They are averaging 7.3 penalties a game, which is slightly above the NFL average of 6.52 (though well below the Raiders' league-leading 10 per game). Most of the 49ers' penalties have been holds or false starts, however. The worst of the bunch have involved chop blocks, including a controversial one in Baltimore and a less controversial one Monday against the Steelers. But at least those penalties involve a 49ers blocker trying to protect a 49ers quarterback, not smash an opposing quarterback.

The team's leading tackler, linebacker NaVorro Bowman, is not sure it's a conscious thought for a player to -- in the heat of a fast and furious game -- switch gears and purposely go non-head-hunting. Bowman thinks it has now just become part of his overall mentality as he approaches each game. And he admits that the NFL's eagerness to issue fines has had an effect.

"The league is taking money," Bowman said. "So you do make an effort to avoid it. In some ways, it's just learning from other people's mistakes."

In a sense, each week of this NFL season has become a mini-ethics seminar on the exact purpose of defensive football. Whitner isn't afraid to admit that the goal of he and his teammates is not merely to stop an opponent from gaining yards and scoring points, even if that is supposed to be the stated mission.

"It's also to inflict fear," Whitner said. "I think there's a psychological part of it. If you hear that you are going to play against a team with Patrick Willis, it does something to your psyche, knowing he is going to hit you and hit you hard."

But a tackler can also do all of that by hitting opponents in the chest or legs, can't you?

"Yes," said Whitner, then smiled. "You can."

Contact Mark Purdy at or 408-920-5092.