The 49ers, knowing from experience how hard it is to locate and retain pass rushers, signed Ahmad Brooks to a 6-year, $44.5 million contract, with $17.5 million guaranteed. That’s a pretty hefty chunk to one of the few starters on defense who didn’t make the Pro Bowl or an All-Pro team, but the 49ers showed their cards early on this off-season.

The 49ers are going to build their defense from front to back. The front seven was this team’s overriding strength in 2011, and with the NFL’s structure (both in terms of positional payroll slotting and rule changes tilted toward helping the passing game), there was no way they were letting Brooks hook on with another team.

With conditioning and character issues completely behind him, Brooks has developed into one of the top free agent outside linebackers available, and a couple of the others in the top 5 (according to Walter Football, anyway) are Manny Lawson and Leroy Hill, who was just arrested for the third time in three years (on Saturday he was arrested for possession of marijuana, the second such arrest for Hill).

Guys with 18 sacks over the past three seasons aren’t readily available, and they never come cheap. Brooks would have been the Niners’ best pass rusher on several of those teams during the Mariucci, Erickson, Nolan and Singletary years. Just because Aldon Smith’s arrival meant he wasn’t the best pass rusher in 2011 doesn’t make Brooks any less valuable to the 49ers or any other team.

Assuming the 49ers keep Dashon Goldson…

I heard about the Brooks signing right before I met David Fucillo at Flipper’s (for probably the last time before he heads off to Washington D.C. in a couple weeks to take a full-time job with SB Nation … congrats, Fooch!). We both agreed: after the Brooks signing, there’s a good chance Carlos Rogers will walk. It isn’t a sure thing by any means, but here’s what re-signing Brooks tells me: Trent Baalke and the coaching staff probably feel like their defensive front is so good, they don’t need to overpay for any cornerback.

So perhaps the 49ers will be looking for a bargain replacement for Rogers, after all. While the Niners have cap room to spare, raises have already been awarded to Brooks and C.J. Spillman, and Alex Smith and Goldson probably aren’t far behind. If the 49ers are looking to spend some free agent money on anyone who played elsewhere in 2011 — like a FA wide receiver or some help for the right side of the offensive line — there might not be the kind of money left over to bring Rogers back at elite corner prices.

That doesn’t mean Rogers is gone for sure. He had a very good season, the best of his career, and spoke of wanting to return. But if he is to come back, it seems likely now that it’ll be if the 49ers wait out the market and Rogers doesn’t get any hefty offers.

The Niners’ new advantage

Unsurprisingly, when Brooks spoke with the media about re-signing with San Francisco, he mentioned the 49ers’ defensive superiority as a reason why he signed before becoming an unrestricted free agent. Not only did the Niners give Brooks a shot after the Bengals cut him, they provide the environment and surrounding talent to allow Brooks’ career to continue ascending.

“Getting as much money as you can sounds good but at the same time what team is going to give you the best opportunity to win. I feel the 49ers are heading in the direction of being the best team.”

What does it mean to be part of that linebacker corps?

“It means a lot. NaVarro and Pat are two great inside linebackers and they complement each other well. I’m glad to be on outside of them playing with them. We’ll be a great defense for a long time, as long as we continue to draft guys like Aldon and NaVarro. The defense will be the best in the NFL.”

While the NFL’s salary cap can prohibit dominant teams from keeping every valuable player, the league’s non-guaranteed contracts gives players an incentive to play where they’ll succeed. What good is a 6-year deal if you’re cut after two or three seasons and your reputation is nowhere near what it once was, either because your production sunk or you’ve become associated with losing football (or both)?

If the 49ers do what they surely believe they can next season (win the Super Bowl with the league’s No. 1 defense), everyone looks great. Players keep their jobs, players get raises, love and endorsements, and glean satisfaction from their work.

When Rogers spoke about taking a “team discount,” he wasn’t lying. He knows his career will bring higher returns in every way if he plays in front of a great pass rush. One which doesn’t force him to cover great receivers for over three seconds consistently, which is almost impossible for any defensive back these days. Now that we know how much the Niners value a good pass rusher, the focus shifts to what they think of the smaller, faster guys behind the front seven.

One last note: Brooks mentioned Ray McDonald several times during his media session. Before the 2011 season, McDonald (like Brooks, a solid player but by no means a star) signed a similar deal to Brooks’, only cheaper: 5 years, $20 million. McDonald responded with a monster season. A monster season relatively few talked about, but he was instrumental to the 49ers’ otherworldly success — especially against the run. From a Feb. 16 post on McDonald by Pro Football Weekly:

“It came down to keeping (NT) Aubrayo Franklin or McDonald (as the left end), and there’s no doubt they picked the right guy,” one team insider said of McDonald, who has to rank very highly among the league’s most unsung performers in 2011. “He’s a very dedicated guy who stayed on the field and has really improved the last two seasons. The season before last, he would get to the pocket but have a hard time finishing. This year was a much different story (team-high 14½ tackles for loss). And he showed real toughness overcoming a nagging hamstring injury.”