Defensive tackle Vince Wilfork and linebacker Jerod Mayo may be the Patriots' most consistent defensive contributors. Yet the performance of McCourty will be what makes or breaks the team in 2012.
The 2010 first-round draft pick has experienced some peaks and valleys during his two NFL seasons.
During his rookie year, McCourty intercepted seven passes and was voted to the Pro Bowl. In his sophomore campaign, the Rutgers product nabbed just two picks, and according to Stats LLC (via Jamison Hensley of ESPN.com), allowed 1,115 receiving yards.
When McCourty excels, so does the defense.
Pro Football Reference reports that two years ago, New England's defense was eighth best in points allowed and conceded 258.5 passing yards per game.
When McCourty struggles, the defense follows suit.
NFL.com data indicates that in 2011, the Pats' D ranked 15th in points allowed and gave up 293.9 passing yards per game.
"He was asked to handle more receivers one-on-one in his second season and wound up as one of the least effective cornerbacks in the league," said Gregg Rosenthal of NFL.com. "Things got so bad that McCourty had to be moved to safety."
Safety is a relatively weak position for the Pats, but it has been bolstered thanks to some offseason acquisitions.
In March New England signed ex-San Diego Chargers safety Steve Gregory, who could very well start alongside Patrick Chung. In addition, the team chose versatile Illinois safety Tavon Wilson in the second round of the 2012 NFL draft and Ohio State's special teams extraordinaire Nate Ebner in the sixth round.
With the benefit of fresh faces, focusing on cornerback and letting the safety matter unfold might be best for McCourty.
After all, McCourty battled more than wide receivers last season—he fought a separated shoulder. The injury hampered the defensive back's play and caused him to miss two regular-season games.
Despite the injury, McCourty was used heavily on defense in 2011. In fact, Mike Reiss of ESPNBoston.com's research shows that McCourty played 84.2 percent of defensive snaps—good for third most on the squad behind Kyle Arrington and Vince Wilfork.
D-Mac's shoulder is improving, but can the same be said for his abilities as a football player?
Who is most critical to the success of the 2012 Patriots' defense?
That question remains unanswered.
Newcomers like Marquice Cole, Will Allen and seventh-round draft selection Alfonzo Dennard are all fighting for playing time at corner, while incumbents Kyle Arrington, Ras-I Dowling and Sterling Moore are also looking to make their presence felt.
If McCourty can't rediscover his rookie form, then he may transition to free safety once again. Although if this occurs, inexperience will become a factor for the rest of the cornerback corps.
"That is not an inspiring group," said NFL.com's Rosenthal. "McCourty would make it look infinitely better if he can be above average again."
As a result, the entire makeup and vigor of the secondary is contingent upon McCourty's level of play.
The 5'10", 193-pound DB is still just 24 years old. He is yet to reach his ceiling and hasn't completely honed in his skills.
That being said, he is the team's No. 1 corner and should play like one. 2012 will be the year McCourty will lay it all on the table. Whether the Patriots' defense prospers or fails will largely rely on his production.
"The biggest thing for me now is taking what I learned my rookie year, last year, what I'm learning this offseason, and put it together and try to get better each day at OTAs," McCourty told reporters at Gillette Stadium on May 24.
Safety or cornerback, his position is not solidified. However, one thing is for certain:
Devin McCourty's time is now.