Nick Fairley is headed to St. Louis. (Getty Images)

Former Detroit Lions defensive tackle Nick Fairley has agreed to a contract with the St. Louis Rams. He's not the most high-profile defensive player to leave Detroit this offseason -- that would be Ndamukong Suh. But he's a good player who helped the Lions to a very strong defense when he was on the field for the first half of last season. Here are a few things to know about Fairley and his new deal.

1. The money: Fairley signed what can reasonably be termed as a "prove-it deal," a one-year pact that pays him $5 million in base salary and can be worth up to $7.5 million with incentives. Whether he ultimately collects $5 million or $7.5 million, the salary makes him one of the 10 highest-paid defensive tackles in the league next season, according to Spotrac. St. Louis had just over $25.6 million in cap space prior to the Fairley signing, so they've still got plenty of room on the books to pursue additional free agents to fill their various holes.

2. Fairley's career: There's a reason Fairley got a one-year, prove-it deal. He's been very injury prone throughout his career, playing in only 46 of a possible 64 games in his four seasons with the Lions after being drafted 13th overall out of Auburn in 2011.

In those 46 games, Fairley recorded 98 trackles and 13.5 sacks while adding four forced fumbles and three recoveries. His two best seasons were 2012 and 2013, when he played 28 games and totaled 69 tackles and 11.5 of those 13.5 career sacks.

He's dealt with weight issues during his time in the NFL as well, and the Lions declined his fifth-year option last offseason in hopes that it would motivate him to get in shape and have a productive 2014. That is pretty much exactly how it played out through the first part of the season, but then he suffered a knee injury that kept him out until the playoffs.

3. The market: Fairley was the second-ranked defensive tackle and 15th-highest ranked player on our free agent big board. With Terrance Knighton and Stephen Paea headed to Washington, Dan Williams signing with the Raiders and Jared Odrick agreeing to a contract with the Jaguars, the highest-ranked remaining defensive tackle options are B.J. Raji (51), C.J. Mosley (58), Tommy Kelly (78) and Pat Sims (80).

4. How he fits: Fairley joins a stacked defensive line that includes 2014 Defensive Rookie of the Year Aaron Donald and 2013 First-Team All-Pro Robert Quinn, as well as Chris Long, William Hayes and Michael Brockers. The Rams cut Kendall Langford loose earlier in the offseason (he signed with the Colts) and Fairley should step in to replace those snaps. This crew should be a nightmare for opposing quarterbacks and running backs alike, with Quinn, Long and Hayes setting the edge while Donald, Fairley and Brockers push the pocket up the middle.

St. Louis still has to work on the back seven aspect of their defense, but having a defensive line this strong will help. The pass rush and cover guys are necessarily intertwined, as defensive backs don't have to cover for quite as long if the quarterback is getting knocked down quickly. They'll likely still pursue upgrades at linebacker, corner and safety, but at least they have the luxury of knowing they're set up very well up front.