The Buffalo Bills have been one of the best teams in the NFL over the last three years, posting a 37-12 regular season record during this stretch. Yet the historically-maligned franchise has been unable to get over the hump and reach the Super Bowl, falling twice in the division round and once in the AFC Championship game.

The team once again enters 2023 as one of the favorites in the AFC. And with Josh Allen under center, Buffalo returns an offense that was second only to the Kansas City Chiefs in 2022 in terms of points and yards gained per contest.

The Bills also boasted one of the most underrated defenses in the NFL. Buffalo ranked sixth in yards allowed per game and gave up the second-fewest points per contest. Yet the Bills gave up 58 points across their two postseason contests, ultimately leading to an exit in the divisional round against the Cincinnati Bengals.

The franchise strengthened its defense in the off-season by bringing in edge rusher Leonard Floyd to team up with the ever-dangerous Von Miller, but there is still room for improvement on that side of the ball. As the start of training camp looms in the next month, who can the Bills look to add on defense as they look to pursue that elusive Super Bowl title?

Bills: 1 perfect move to fill out roster before training camp

Sign free agent cornerback Marcus Peters

The strength of the Bills' secondary lies in its safeties. Jordan Poyer and Micah Hyde might be the best safety duo in the league — combining for 10 interceptions and 12 tackles for a loss when both healthy in 2021. They were first and second-team All-Pro, respectively, that year. As for the cornerbacks, they were not quite so successful in 2022.

Tre'Davious White, an All-Pro player in 2019 and 2020, is the unit's star. He missed half of Buffalo's games over the last two seasons but held quarterbacks to a 59.9 passer rating when thrown in 2021 and a respectable 75.8 passer rating in 2022. Outside of white, the Bills' corners have been young and inconsistent.

Defensive players are often difficult to judge, but Pro Football Focus' player grades gives us the best idea of how these players performed on the field. Rookie first-round pick Kaiir Elam struggled in his debut season, with a PFF grade of 56.7 — putting him at replacement level. Dane Jackson and Christian Benford (another rookie) also had scores in the 50s. In fact, Taron Johnson was the only Bills corner other than White to earn a score in the 60s (68.3) which still only puts him in the “average” category.

This secondary is in need of an upgrade, and the best free agent left on the market is Marcus Peters. Peters missed all of 2021 with an ACL tear, yet returned in 2022 and posted a modest PFF grade of 67.7 — which would have been good for second among Buffalo corners. The former Baltimore Raven is a ball-hawk, averaging better than four interceptions per season in his time as a pro while reaching the end zone on nearly 20% of his returns.

When healthy, Peters was among the best corners in the game, earning a trio of Pro Bowl nods and two first-team All-Pro nominations. Even if he does not return to that elite level, Marcus Peters is still an upgrade at the cornerback position for the Bills and a valuable veteran presence for the Buffalo defense.