Each NFL team's offseason is filled with small moves and marginal personnel decisions. Sometimes, that series of small moves will build a winner. But a big, bold move always helps, by dramatically improving talent at an important position or changing the overall direction of the franchise.

In this series, Football Outsiders goes division by division to suggest a bold move that each team could make to get better this offseason, either in the short or long term. Stories may refer to Football Outsiders' DVOA (defense-adjusted value over average) metric, which takes every play during the season and compares it to a baseline adjusted for situation and opponent. It is explained further here.

San Diego Chargers: Sign Ndamukong Suh in free agency

As long as Philip Rivers is healthy, the San Diego offense will be efficient. The struggles have been on defense. After ranking 32nd in defensive DVOA in 2013, the Chargers climbed to 24th last season -- but there's obviously still plenty of room for growth.

Free agent Ndamukong Suh is a three-time All-Pro defensive tackle, and will be only 28 years old this season. Maybe he never leaves Detroit, but any team in the range of contending for the Super Bowl has to consider a player of this caliber. Yes, he is known as a dirty player, but he has been pretty clean off the field -- and impactful on the field. Detroit's run defense was ranked first in DVOA this season, and was one of the stingiest this century.