FOXBOROUGH, Mass. -- How will the Patriots replace the void left at middle linebacker while Jerod Mayo recovers from a left knee injury? If history is a guide, fourth-year linebacker Gary Guyton will have every opportunity to make the most of his good friend's misfortune.
Jump back to the start of the 2009 season, when Mayo suffered a sprained medial collateral knee ligament -- the same injury that Mayo reportedly sustained Sunday -- and sat out nearly a month before making an earlier-than-anticipated return in Denver.
During the four-game stretch Mayo was unable to start, Guyton took over the middle linebacker role in a 4-3 alignment. The Patriots deviated from their more familiar 3-4 defense that season to facilitate the switch. This season, they're operating out of a base 4-3, which could simplify matters.
Complicating matters, however, is the fact that New England's defense ranks 32nd in total yards allowed, so the loss of a captain who is one of the top players on that side of the ball is daunting.
For Guyton, it's a chance to earn back some of the playing time that's eroded since 2009, when he started all 16 games and played a whopping 874 snaps (82.6 percent of New England's total defensive snaps, according to the analytical stats site Pro Football Focus).
That number dipped to 675 snaps last season (57.6 percent of total snaps), with rookie Brandon Spikes earning some of Guyton's early-down action as a run-stopper.
Now it's likely that Guyton will not only step in for Mayo, but could also assume an every-down role that might land him responsibilities as the defense's chief play-caller.
"Gary basically replaced Jerod in our regular defense and then we had some other guys in sub defenses," Patriots coach Bill Belichick said Monday when asked about how the Patriots divided Mayo's snaps Sunday. "So we had some different packages in there, it wasn't a Ferris wheel of guys. There was actually a plan there, believe it or not."
And the plan will likely start with Guyton. Even after watching one of his best friends go down Sunday, Guyton wasn't overwhelmed by the significance of losing a captain as part of a rash of injuries that have impacted the team.
"It's football," Guyton said. "You just come in and do your job."
Even so, replacing Mayo is virtually impossible. The 10th overall selection in 2008, Mayo won Defensive Rookie of the Year honors that season, and last season he was voted first-team All-Pro and made his first Pro Bowl after registering a career-high 114 tackles.
While their paths to the NFL couldn't be more dissimilar -- Guyton went undrafted out of Georgia Tech before latching on with the Patriots as a free agent -- the two have been attached at the hip in the middle of New England's defense for much of the past three seasons, which might actually ease the burden of Mayo's absence.
"Gary and Jerod came in together," Belichick said. "They're very close personally and [they] play well next to each other. They have great communication and both guys kind of can do what the other one does. They flip assignments and positions regularly on the defense, just to change up the looks, just to have a different guy doing it -- within the structure of the defense, having different guys doing it to makes the offense read it differently and so forth.
"I think Gary has good experience and he knows all the positions -- any inside linebacker part of the defense, regardless of what our front is and so forth, he's pretty adept and he's a real sharp guy."
During his weekly appearance on Boston sports radio WEEI, Belichick pointed out that Mayo has been limited in practice the last couple of weeks with a thigh injury, which has given other linebackers a chance for more practice reps. Those additional reps might further ease the loss of Mayo moving forward.
Belichick stopped short of anointing Guyton the starter in place of Mayo.
"We'll see what the game plan is going forward here, but certainly Gary has had a big role in our defense over the last three years and I'm sure he'll continue to," Belichick said. "He's a key guy for us and he's done a good job. He's done various things: played in sub defenses, played in regular defenses, played our middle linebacker spot, played our other inside linebacker spot, what we'll call 'the will.' He's done a lot of things."
Guyton battled some hamstring issues earlier this season, which forced him to sit out the Week 2 game against the Chargers. A player who thrives on speed, Guyton needs a healthy hammy in order to help replicate Mayo's production.
He'll have some help. Belichick noted the "big jump" that Dane Fletcher has made since arriving as an undrafted free agent (sound familiar?) out of Montana State last season. Fletcher offered a stern critique of himself Monday, saying he'd done "a decent job" as a linebacker this year -- after being converted from a college defensive end -- but said he had plenty to improve on.
Belichick was far more kind in his assessment.
"I think Dane has taken a big jump from where he was last year," Belichick said. "Last year, he came in really as a converted defensive lineman. [He] made an impact for us in the kicking game. At other points in the year, [he] did some things situationally on defense.
"This year, he came in and played inside linebacker right from the beginning of the year. He's way ahead of where he was last year. There's just really no comparison. He got a good year of experience and he definitely built on that. He's a smart guy, works hard, he's in good condition, he's a good athlete, runs well [and] he's physical."
History suggests the loss of Mayo won't be easy to overcome. The Patriots went 2-2 during his four-game absence in 2009, including a 16-9 loss to the Jets -- whom the Patriots welcome on Sunday -- in the first game Mayo sat out.
This may be the most important opportunity of Guyton's career, particularly in a contract year. His play in 2009 helped him earn a two-year extension that is set to expire after this season. A larger role could mean a larger payday for Guyton next summer.
Chris Forsberg covers the Patriots for ESPNBoston.com.