Isaac Sopoaga 49ers throwingThe 49ers have given defensive tackle Ian Williams a two-year, $3.2M extension according to Pro Football Talk. Williams only played 32 snaps in 2012, so while the extension is evidence of the 49ers confidence in the young nose tackle, it certainly doesn’t mean they’re done bolstering their defensive line just yet.

They were in the running to land free agent defensive tackle Cullen Jenkins before the former-Eagle signed with the New York Giants on Sunday. Jenkins’ three-year contract with the Giants is worth $8M, with only $3M of it guaranteed. It’s the thrifty kind of contract most expected the 49ers would be floating to try and land Jenkins, so why he passed on San Francisco is up for debate at this point.

There are still plenty of interior defensive linemen out on the market for the 49ers, and their strengths vary. What is the team looking for? A pass rusher, a run-stopper or balance? I threw the question out on Twitter and the consensus answer seemed to be pass rush with an emphasis on “block-clogging.”

The consensus is probably right. San Francisco is letting Ricky Jean-Francois go test the market, and he’ll probably end up elsewhere. Jean-Francois was a strong run-stopper for the 49ers but left a lot to be desired in pass rush. Their interest in Jenkins further supports the theory the 49ers are looking for inside leverage in getting to the quarterback.

Jenkins was one of the first to talk to the 49ers because he was cut, but there are plenty of other options for the team to talk contract with come Tuesday. First, let’s have a look at the man the 49ers will be replacing.

Isaac Sopoaga

Sopoaga had a surprisingly bad 2012 with the 49ers. He accumulated 20 tackles, two sacks, two quarterback hits and two hurries over 335 snaps. He was by far the worst of the staples on the 49ers’ defensive line, grading out -12.5 overall, -8.5 against the run and -4.5 in pass rush on Pro Football Focus. He’s second to last on their free agent defensive tackle list.

Now for a look at some of the possible heirs to Sopoaga’s throne:

Sammie Lee Hill — UFA, Detroit Lions

The fourth year Lions defensive tackle has drawn interest from at least four teams heading into free agency according to Anwar Richardson of Are the 49ers one of them? Hill is coming off of a down year in which he only accumulated 15 tackles and no sacks over the course of 15 games. He graded out poorly in run defense (-2.0) but fared well in pass rush (+7.9). He played 419 snaps, about half the Lions share (pun intended) for most of the year, but his playing time picked up over the last two weeks of the season. Despite his relatively low snap count, Hill still registered two quarterback hits and 17 hurries in 2012. He could be a cheap reinforcement for the 49ers’ defensive line.

Jason Jones — UFA, Seattle Seahawks

Jones is a similar player to Hill. The fifth year Seahawks defensive tackle wasn’t much in terms of run stopping in 2012 (-2.5) with six tackles, one assist and eight stops over limited playing time. Still, Jones was good in the pass rush, grading out +7.7 with four sacks, four quarterback hits and 10 hurries. mentioned the team’s possible interest in Jones, so one way or another he may not escape the NFC West.

Richard Seymour — UFA, Oakland Raiders

Seymour isn’t the uber-expensive big name he once was, and after a lackluster 2012 he could be entering the twilight of his career. He only played half of the season for the Raiders before injuring his hamstring, but in the eight games he played he scored well both against the run and in pass rush. Seymour registered 12 tackles and 12 stops while accumulating three sacks, two quarterback hits and seven hurries. If there isn’t a huge market for Seymour, he would make sense with the 49ers on a short term, incentive-laden deal. The 49ers could draft and groom the defensive tackle of the future behind him.

Desmond Bryant — UFA, Oakland Raiders

No, not Dez Bryant (although it would be a nice addition to the 49ers’ receiving corps). Yes, Desmond Bryant, most famous for being the latest entry in the mugshot hall of fame. Despite his recent brush with the law, Bryant had a solid 2012 season and landed at the top of PFF’s free agent interior lineman list at +16.5 overall. Bryant was only +1.1 in run stopping (which isn’t altogether horrible, because more tackles graded out in the minus than you’d think), but he scored an insane +16.8 in pass rush. He had four sacks, 11 hits and 20 quarterback hurries while accumulating 19 tackles and 21 stops in run defense. He’s 27 years old — four years younger than Sopoaga — and could be an important piece of the 49ers’ defensive line going forward. How expensive will he be? Yahoo’s Jason Cole says the 49ers are among a group of six teams interested (including the Raiders).