Dean, who was one of the dominant defensive players of his era, was a key acquisition by the 49ers in 1981 and helped the team to their first franchise championship.
While he only played in just 11 games for the 49ers in 1981, Dean was chosen as the UPI's NFL Defensive Player of the Year.
Dean was a four time Pro Bowl selection and won two Super Bowls (XVI and XIX) with the 49ers. He finished his career with 93 sacks in 141 games and one interception.
From Wikipedia:
In 1981, he was acquired in a mid-season trade and eventually helped the San Francisco 49ers win two Super Bowls in the 1980s. His first game as a 49er was a key match-up against the Dallas Cowboys. Dean played after only a couple of practices and was still able to apply pressure and repeatedly hurried Danny White when he was not recording one of his 3 sacks, in a game won by the 49ers, 45-14. His first action of the season as a 49er was noted by author Tom Danyluk as "the greatest set of downs I have ever seen unleased by a pass rusher". In what have been a game of possum, Bill Walsh, the 49er head coach, said to John Madden, who covered the game, "Fred (Dean) just got here . . . If he plays, he won't play much".
His next home game for the 49ers was against the Los Angeles Rams. The game was won by the 49ers and the first win against the Rams in Candlestick Park, 20-17, as Dean sacked Pat Haden 5 times. He ended the season with 13 sacks, 12 with the 49ers and 1 with the Chargers, prior to his trade.
The 49ers would go on to win the Super Bowl that year, and Steve Sabol (NFL Films) is quoted in 2006 as saying that Dean's acquisition was the last meaningful in-season trade, in that it affected the destination of the Lombardi Trophy. San Diego's defense collapsed when Dean departed, giving up 40 points in a loss to the Cincinnati Bengals in the regular season, and 65 total points in playoff games vs. the Miami Dolphins and Bengals. The Charger defense would not return to the top half of the NFL rankings again until the unit was rebuilt in the late 1980s, and the club did not have an effective pass rusher until Leslie O'Neal was drafted in 1986.
In 1983 Dean recorded 17 sacks to lead the NFC and recorded a then-NFL record of 6 in one game, setting that mark during the 49ers' 27-0 shutout of the New Orleans Saints on November 13, 1983. The 17 sacks was a Dean career high, bettering his 1978 total of 15-1/2 with the Chargers.[3]He followed that 1978 season by adding nine sacks in 1979 and 10.5 in 1980. He had recorded 7 sacks as a rookie in 1975.
Dean was also a key player on the 49ers 1984 Super Bowl team, mostly used as a situational pass rusher. During the 1984 season, Dean was reunited with his Charger teammate, Gary "Big Hands" Johnson.
Dean is a member of the Louisiana Sports Hall of Fame.
All-time San Francisco 49ers elected to the Pro Football Hall of Fame
http://www.49erswebzone.com/hof.shtml
Alumni Spotlight: Fred Dean
http://www.49ers.com/pressbox/news_detail.php?PRKey=1312
