Justin Smith, Patrick Willis and NaVorro Bowman get all the headlines, but Isaac Sopoaga is the cornerstone of the San Francisco 49ers defense. The veteran nose tackle deserves a lucrative new contract after his current deal expires at the end of the 2012 season.
The unheralded nine-year pro made the switch to nose tackle in 2011 and quickly became one of the league's best at the position. Moving Sopoaga over the center helped turn an already-talented defense into a truly formidable unit.
At 6'2", 330 pounds, Sopoaga has the powerful frame and natural leverage to occupy double-teams and push the pocket. With Sopoaga holding the middle, Justin Smith is allowed to spend more time rushing the passer than most 3-4 linemen enjoy.
Bowman and Willis both benefit from clear lanes of pursuit thanks to Sopoaga's ability to handle 2-gap responsibilities. He was the fulcrum of a run defense that went 14 games without yielding a touchdown in 2011.
There is every reason to believe Sopoaga will do the same. He has improved each season since becoming a regular starter in 2008. The move to nose tackle is likely to add another couple of years to his career.
Pure 2-gappers in the middle aren't easy to find at the pro level. If Sopoaga enjoys another stellar campaign this season, then he should be rewarded with a lucrative, long-term contract.