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For Nolan Carroll and the Philadelphia Eagles, what a difference a year makes.

Upon signing with the Eagles in March 2014, Carroll had been a free agent on the open market for three weeks. The former Miami Dolphins cornerback wound up playing the whole season in Philadelphia’s dime package, unable to beat out an ineffective Bradley Fletcher for the starting job.

Then the organization used its 2015 second-round draft pick on Eric Rowe out of Utah, seemingly cementing Carroll’s role as a backup.

But when the Eagles showed up for offseason workouts, Carroll—not Rowe—was the starter opposite Byron Maxwell. As it turned out, that wasn’t just the coaching staff making the rookie earn his spot on the depth chart, either.

By all accounts, the sixth-year veteran established himself as the man to beat over the course of the offseason.

Carroll Career Stats YR TKL PD INT FF 2015 12 3 0 0 2014 32 4 0 0 2013 47 11 3 0 2012 53 5 0 1 2011 32 4 1 0 2010 3 2 1 0 NFL.com

Now Carroll is one of the unsung heroes of a Philadelphia defense that’s carried its struggling offense through three weeks. He’s easily been the club’s most consistent corner—far more dependable than the high-priced Maxwell coming over from the Seattle Seahawks—and a huge reason why the Eagles are surrendering fewer big plays through the air.

What changed? When speaking with reporters, head coach Chip Kelly chalked it up to simple hard work:

When he got here on April 20, he was our most competitive guy in the weight room. ... I think a lot of guys take that time from the end of the season until April maybe as time off. I think it was obvious to everybody that he didn't take that time off; he worked extremely hard. ... Nolan's experience was as a dime mostly for us. He was really good at it, but could he be an outside corner? And I think he showed to us that he could be an outside corner. He's playing really well right now.

Carroll’s numbers don’t begin to do his progress justice. Through three games, he has 12 tackles, three passes defensed and zero interceptions—not exactly Pro Bowl totals at the cornerback position.

Adam Hunger/Associated Press

However, there were two plays in Sunday’s win over the New York Jets that demonstrated just how far Carroll—not to mention Philly’s secondary—has come.

They were a pair of deep pass attempts played perfectly by the cornerback. He kept the receiver in front of him, drew tight without making too much contact, watched the receiver’s eyes to find out when the ball was coming, then turned and batted it away.

With plays like those, interceptions can't be far around the corner. In fact, Carroll made a similar play in a preseason game against the Baltimore Ravens, tracking a receiver downfield and tipping the ball into the air—intentionally—to safety Walter Thurmond for the pick.

Last season, the Eagles led the NFL in completions of 40-plus yards allowed with 18. That was three more than the next closest team.

Carroll’s emergence has also allowed the Eagles to bring Rowe along slowly. As much as the plan might’ve been to put the 22-year-old in the lineup right away, rookie corners are seldom ready for starting roles. As training camp and the preseason went on, it became increasingly apparent that was probably the case here.

Carroll 2015 Game Log GM CMP ATT YDS TD Wk 1 @ ATL 3 4 48 0 Wk 2 vs. DAL 4 5 26 0 Wk 3 @ NYJ 6 10 51 0 Pro Football Focus

Instead, Rowe has been afforded the opportunity to play limited snaps and develop, and that patience is already paying dividends. Thrust onto the field in dime packages—Carroll’s old role—the first-year defensive back broke up two long throws against the Jets, even pulling down one for a momentum-swinging interception.

Reducing the number of deep completions—or X-plays—was a focus of the Eagles this offseason, which led to the hiring of defensive backs coach Cory Undlin.

So far, Kelly noted that the change has been a success:

They are doing a better job than we did a year ago. We still need to clean that up, though. ... I've seen improvement from Game 1 to Game 2 to Game 3, so we just need to continue. They took a couple shots. Eric Rowe made a nice play on a breakup and then Rowe had an interception. And they took a shot on Nolan and I thought Nolan made a really nice play on the deep ball to [Jets receiver] Brandon Marshall. So, I've seen improvement, but we need to continue to get better.

Much of that improvement can be attributed Carroll, whether it’s because he’s taken the pressure off other defensive backs or through his own fine performance. It certainly is surprising to see a 28-year-old player make this kind of leap with 27 career starts entering the season, but the Eagles will take it.

Whether Carroll holds up in coverage for the rest of 2015 remains to be seen. Thus far, he seems beyond capable of holding his own on the outside.

Unless otherwise noted, all camp observations acquired firsthand.