It has been a tough struggle for Nate Allen. A second-round draft pick in 2010, Allen stepped right into the starting lineup. He was an aggressive, hungry player who had a knack for timing up the blitz, playing well in coverage and providing sure tackling.

There's a video clip on NFL.com of Allen blitzing off the edge in a Thursday night game against Houston. The Eagles led the game, 34-24, and the call was for Allen to go after quarterback Matt Schaub from the blind side. Allen timed it right, raced in on Schaub untouched and used his right hand to knock the ball loose from Schaub. The Eagles recovered the fumble. Game over.

Allen looked like he had a chance to be the next great safety here. A knee injury on December 19, 2010 -- Allen ruptured the patellar tendon in his right knee in the game against the Giants that everyone recalls for DeSean Jackson's game-ending punt return -- set Allen back through the 2011 season.

Since then? Well, Allen has emerged in 2013. He's a starting safety for the Eagles, still, and if you were to list the "surprises" of this season, Allen's name and his solid play might very well be at the top of the list.

"I've grown up, gone through a lot of experiences, had a lot of ups and downs and I think that now, everything is coming together right now and we're playing well as a unit," said Allen. "Defense and offense, really. We just have to keep rolling and I just need to keep getting better."

Allen's steps forward this season have been easy to see. He's much more confidence in his positioning and his timing. The part of this game that was most frustrating was seeing Allen right there to make a tackle, and then seeing him not finish the play as the ballcarrier moved for more yardage.

Was it the knee injury that robbed Allen of that half-instant that makes such a huge difference in the NFL? Was it a lack of confidence? Mind games at this level are very powerful. Was it just that Allen couldn't get back to the level of his rookie season?

"My tackling now is a lot better. My tackling and technique," said Allen who, according to the metrics compiled by Pro Football Focus, has missed just two tackles this season after missing 13 in 2012, 6 in 2011 and 7 in 2010. "It's something we emphasize every day in practice. We work on coming to balance even when we don't have pads on. We're balanced and ready to make a tackle and we're carrying that through to games. My practice habits have improved a lot and that has taken a lot of work. It's about muscle memory now. We do it every day. We emphasize how important technique is. The coaches stress it.

"And when it comes to game day, there is no letup. It's full steam ahead with a lot of confidence."

It's showing on the field. The defense has allowed no more than 21 points in any of the last seven games, and the takeaways are up and the red-zone efficiency is fantastic. Opposing offenses have scored touchdowns only twice in the last 12 trips inside the Eagles' 20-yard line, and Allen's improved play is a primary reason.

"I feel a lot more confidence and sure of my assignments," said Allen. "It's really the whole defense playing together, though. We've all stepped it up, and we all have a better understanding of the defense and what the coaches want.

"But it's never perfect and that's what we all strive for. We're executing better, playing well as a group. That's what counts."

Allen has been challenged in just about every way by the team. Patrick Chung and Kenny Phillips signed on in free agency, and Earl Wolff was drafted last April. As December arrives, here is Allen in the starting lineup, playing good football. Defensive coordinator Bill Davis has called on Allen to be a leader on the defense and has asked him to fill a variety of roles.

There is no Wide 9 up front that leaves gaping holes for a safety to fill with a running back in the open field. There is no changing of coaches in the middle of the season. There is no panic with Davis and the coaching staff.

Instead, there has been an emphasis on learning together and steady, as-a-group growth.

"I think the scheme change is putting less stress on safeties to fill an interior gap, so he can focus more on the pass," said Davis. "Secondly, I think his angles and the fundamentals that (defensive backs) Coach (John) Lovett and (assistant defensive backs) Coach (Todd) Lyght have been teaching in the tackling, and we're teaching tackling every day.

I think the one thing in tackling that we saw from a year ago is everything was an arm tackle because the head placement was wrong, and I think we work hard on the head placement, which turns an arm tackle into a body tackle, and I think Nate has benefitted along with the rest of them from that."

So, then, the energy that Allen exudes as he enters the field, as he waits for his turn on the sidelines, all of that is part of the in-game Allen. He's sure of who he is, sure of his responsibilities and playing good, confident football. Want a surprise from 2013 to date? How about that Nate Allen is playing his best football for a defense that has collectively jumped up its game in the last two months.