He could also be a much-needed deterrent.
Last season, offenses looked to exploit the Ravens' lack of depth at cornerback and spread out Baltimore as often as they could. Teams lined up with three or more wide receivers on 650 plays against the Ravens, which was the 10th-most in the league, according to ESPN Stats & Information.
For Baltimore, that was 84 more snaps than in 2013 and 141 more than in 2012. Who could blame offenses for attacking the Ravens this way? Teams chose not to run against the 670-pound wall of Haloti Ngata and Brandon Williams and instead go after unproven cornerbacks Asa Jackson, Rashaan Melvin, Dominique Franks and Chykie Brown. The Ravens were forced to play their nickel defense 60 percent of the time last season, which put a strain on the thinnest position for Baltimore.
Baltimore went through a long list of players at the No. 3 cornerback spot, and the Ravens were so desperate that they used struggling safety Matt Elam in that role at times. The Ravens' nickel defense ranked 15th in the NFL last season, and quarterbacks had a 86.6 passer rating against Baltimore when it used five or more defensive backs.
The signing of Arrington should improve the Ravens' success on pass defense and could change how offenses plan to go after Baltimore. Arrington ranked No. 36 among cornerbacks by Pro Football Focus, and he was part of a Patriots' nickel defense that finished No. 8 last season.
Of course, there are going to be teams who will spread out Baltimore because that's what their offense is designed to do, and the Ravens and Arrington will get tested immediately in that regard. Baltimore's first game is against the Broncos, who lined up with three or more receivers 70 percent of the time. Only three others teams (the Miami Dolphins, Green Bay Packers and San Diego Chargers) did so more often than the Broncos.