But when Fangio arrived in San Francisco, he found another level of dominance.

Consider the following transformation: When Fangio arrived to work with the 49ers, the unit was coming off the 6-10 season in which it ranked 16th in points allowed per game, 13th in yards per game, 20th in takeaways and 24th in passing yards per game.

Just a year later, Fangio's defense ranked second in points allowed — making a jump from 21.6 points per game to 14.3 points per game — fourth in yards per game, and 16th in passing yards per game. That 2011 49ers team also led the NFL in rushing yards allowed per game (77.3 ypg) and takeaways. A year after forcing 22 turnovers, Fangio's San Francisco team forced 38 in 2011.

He sustained that success for the better part of his four-year tenure with the 49ers. San Francisco ranked in the top three scoring defenses during Fangio's first three seasons in the Bay Area, and those units also finished top five in yards per game and rushing yards per game. After 2011, his rushing and passing defenses never finished worse than seventh in the league.

And then there were the takeaways. Following 2011 — when his defense finished first in the league — he guided the 49ers to three straight performances that ranked in the top half of the league, including two top-10 finishes in 2013 and 2014.

Perhaps it's no surprise that Harbaugh and Fangio's team experienced quite a bit of success. After their 13-3 season and NFC Championship appearance in 2011, the 49ers made it to Super Bowl XLVII and then made another NFC Championship appearance during the 2013 season.