Smith's former contract was set to expire at the end of the 2013 season, and despite his age (he turns 34 in September), he would have been one of the hottest free agents on the market. Smith recorded 65 tackles and three sacks last season, although a late-season triceps injury forced him to miss his first game since 2002.
Regarded as one of the best 3-4 linemen in the league, Smith is a key player in Jim Harbaugh's defense, and his presence on the line allows Aldon Smith to run free and terrorize quarterbacks. The defense was noticeably weaker last season when Smith was forced to sit out.
Smith has 536 tackles, 32 sacks, one interception and seven forced fumbles since joining the 49ers in 2008.