There is no question Franklin has played a major role in both the construction and occasional success of San Francisco's defense since he joined the team as a free agent in 2007.
Back then, Franklin was a relative unknown, having spent his first four NFL seasons with the Baltimore Ravens, where he recorded just one start in 36 games played.
But then-49ers coach Mike Nolan, who was Baltimore's defensive coordinator when Franklin broke into the league, thought Franklin had the potential to fit in nicely at nose tackle in the kind of 3-4 defensive scheme Nolan was trying to build in San Francisco.
Nolan was right. And Franklin is an unknown no more.
Franklin, in fact, is considered one of the top players to hit 2011 NFL free agency after a new CBA is reached and the lockout ends. Scout.com has Franklin ranked as the No. 17 free agent available regardless of position, and No. 2 among defensive tackles behind Haloti Ngata, who already has been slapped with the franchise tag by the Baltimore Ravens and won't be going anywhere.
Franklin has similar standing among other free-agent rankings. The Sporting News says of Franklin in its rankings, "He's the best of the 3-4 nose tackles available."
And that will make Franklin very expensive for the 49ers or any other team that signs him once the bell sounds on the open market this summer.
The 49ers became resigned to this fact long ago. They slapped Franklin with the franchise tag last year, and he played the 2010 season on a one-year, $7.033 million tender contract. That's a hefty price tag, and the 49ers declined to designate Franklin as their franchise player this year because of the prohibitive cost involved with doing so.
That could be an indication the 49ers are prepared to let him go. Franklin turns 31 in August and there have been questions about the shape in which he keeps his body. But there can be no denying what he has meant to the San Francisco defense, and few questions about the quality of his play while anchoring the team's defensive front.
Franklin started all 16 games in 2010 for the second consecutive season – he started 15 games in 2008 and 13 in 2007 – and once again had a stellar season, finishing with 86 tackles. That was just two short of his career-high 88 tackles in 2009 – the season during which Franklin truly established himself as a force, persuading the Niners to make him their franchise player.
Even more significantly than those numbers, Franklin has been stout at the point of attack, a consistently immovable object that helped clog the middle and keep big offensive linemen off middle linebackers Patrick Willis and Takeo Spikes, allowing Willis in particular to roam free, make plays and become the NFL's leading tackler in 2007 and 2009.
The 49ers ranked sixth in the NFL against the run last season and second in the league in rushing average per carry allowed. In a 3-4 defense, the nose tackle is significant in making that happen by holding the point of attack, something Franklin has done very well since becoming a 49er.
The Franklin breakdown
2010 performance: Started all 16 games for the second consecutive seasons and was strong at the point of attack while spearheading San Francisco's elite rushing defense. Recorded 86 tackles and recovered one fumble but was equally important to the 49ers by occupying blockers in the team's defensive scheme.
2010 season grade: B-plus
Why he's worth keeping: The 49ers need a big nose tackle like Franklin to clog the middle and keep blockers off All-Pro linebacker Patrick Willis. Franklin has performed these roles capably if not exceptionally for the past four seasons and his departure would leave a glaring void in the solid front wall the Niners have built for their defense in recent years.
Why he's not worth keeping: Though he has remained durable, Franklin's body makeup and the condition he keeps himself in suggests he could break down at any time. He also isn't much of pass rusher, recording just three sacks in his four seasons with the Niners. And then there's the exorbitant price tag Franklin is likely to attract as one of the top free agents on the open market this year, a deal that could pay him more than he's worth to the team.
Where he would fit with the 2011 49ers: Franklin would fit right in the middle of San Francisco's defensive front as the starter at nose tackle, a role he has performed admirably the past four seasons. His return would bring a lot of stability and continuity along a quality defensive line that includes starting ends Isaac Sopoaga and Justin Smith.
How he would be replaced: The 49ers' best option probably would be to move the 330-pound Sopoaga from left end to nose tackle, where he has played earlier in his career. Sopoaga is a good fit on the nose and he could greatly alleviate the loss of Franklin, though that move would create another void at the position vacated by Sopoaga. Another possibility is young Ricky Jean Francois, who occasionally spelled Franklin at nose tackle last season. Francois flashes promise but remains raw and unproven, and at 295 pounds he's too light for regular duty on the nose. It's possible the 49ers also could look to bring in a less-expensive free agent should Franklin depart.
Market interest level: High. Franklin is rated as one of the top veterans available in free agency this year regardless of position, and some consider him the No. 1 player available at defensive tackle. There are other teams out there prepared to offer him a lucrative contract the moment the NFL lockout ends.
49ers interest level: Attentive. The high cost of the franchise tag prevented the 49ers from locking up Franklin earlier, but the team would like him to return and is willing to pay a fair price. However, the 49ers at this point are pretty much sitting back and waiting to see what kind of money other teams will throw at Franklin before they make their move. They are wary of tying up too much money in Franklin with a long-term deal.
The 49ers should certainly make a play for Franklin, but it's unlikely they will get any discounts because of his previous association with the team. Franklin is looking for the big payday, and the Niners have to seriously examine how much he is worth to them as they continue their quest to build a winner. Sopoaga provides a good insurance plan at nose tackle, but the 49ers run the risk of losing a key cog in their defensive approach if Franklin doesn't return. That said, the team should let him go if the price is just too steep, and invest that money in another veteran who will step in as a key new part of the defensive line and perhaps have more seasons to give the 49ers in the future.