However, there are still quite a few players set to become free agents in 2014 and 2015 that the team should think about locking up long term.
With the number of players holding out due to stalled contract negotiations rising each and every year, the Bills need to not only think about their current unrestricted free agents, but their future ones as well.
This slideshow overviews four players that deserve contract extensions in the 2013 season.
The Buffalo Bills selected Alabama's defensive lineman, Marcell Dareus, with the No. 3 overall pick in the 2011 NFL Draft. While the 2011 draft class supplied players that produced more in terms of statistics, there is no questioning that Dareus is becoming an impact player for the team.
In two seasons with the Bills, Dareus has racked up 82 tackles and 11 sacks. The 23-year-old defensive tackle has batted down eight passes at the line of scrimmage and is developing into a complete defensive lineman in the National Football League.
Dareus is in line to earn base salaries of $2.2 million in 2013 and $3.1 million in 2014, while his pro-rated signing bonus will pay him $3.35 million in each of those seasons.
He will be an unrestricted free agent following the 2014 season at the ripe age of 25. The Bills have already locked up 29-year old defensive tackle, Kyle Williams, through the 2017 season, and it would be intelligent to do the same with Dareus.
The Bills drafted center Eric Wood out of Louisville with the No. 28 overall pick in the 2009 NFL Draft. The 26-year old interior offensive lineman is entering the final season of the five-year deal he signed following the draft.
Standing 6'4" and weighing 310 pounds, Wood has developed into one of the top centers in the National Football League. He played right guard with the Bills in 2009 and 2010, before making the transition to the pivot in 2011.
Wood has suffered three major leg injuries that ended his 2009 and 2011 campaigns, and injury concerns may drive down his value a bit. He's missed 17 games in four seasons due to these injuries, but when Wood has been on the field, he's been effective.
According to ProFootballFocus, Wood was the seventh-rated pass blocking center in the entire National Football League in 2012. He allowed just three sacks and 10 pressures this season, and has given up just eight sacks in his career.
The Bills locked up guard Kraig Urbik before the end of the season for four years, and the team's expected to re-sign unrestricted free agent Andy Levitre this offseason. Keeping the three together makes sense, as they've been one of the more cohesive units in the NFL.
While defensive tackle Alex Carrington isn't a starting player on the Buffalo Bills' defensive line, he has made quite the impact in his third season. Drafted in the third round of the 2010 NFL Draft out of Arkansas State, Carrington finally seemed to catch on in 2012, serving as a rotational defensive lineman.
He only recorded 19 tackles this past season, but he added two sacks, batted away three passes and forced a fumble. His main impact came on special teams, where he blocked four field goals and got his hand on another that eventually went through the uprights.
Carrington was ranked as ProFootballFocus' seventh most productive pass-rusher among 4-3 Defensive Tackles, as he generated 18 pressures in 181 pass-rushing snaps.
Carrington will earn $575,000 in the final year of his rookie contract, and while he shouldn't be signed to a major deal, he should be brought back.
Scott Chandler was acquired off of waivers in the 2010 season and has since become arguably the greatest tight end in the history of the Buffalo Bills. In his two seasons with the team, he's made 82 receptions for 968 yards and scored 12 touchdowns.
Chandler will earn $2.05 million in the final season of the two-year, $5.45 million deal he signed prior to the 2012 season. He suffered a torn ACL in the final game of 2012 against the Miami Dolphins, and it remains to be seen exactly how much time will be missed in 2013. However, the 27-year old has been extremely consistent for the team, and at 6'7", 260 pounds, there aren't many tight ends of his size that have his athletic ability.
If he's medically cleared to play, Chandler should be retained during the 2013 season before another franchise has the opportunity to snag him away in free agency.