When the Eagles released left guard Evan Mathis last week, it wasn't a huge surprise from a personnel standpoint. Mathis had long been unhappy about his contract, which was set to pay him $5.5 million in 2015 and $6 million in 2016. He had asked to be traded, and the Eagles acquiesced, but there were no takers—or, at least, none offering what Chip Kelly deemed a worthy return. And it's not an enormous shock that a guard who will turn 34 in November would be cut, but in Mathis's case, there was a mild uproar given his status as one of the league's best at his position.

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More than anything else, that perception was accelerated by Pro Football Focus's ratings of Mathis's work over the last two seasons—he was their No. 1 guard overall and their seventh-ranked player in 2013, and their No. 2 guard (behind Baltimore's Marshal Yanda) and 59th-ranked player overall in 2014—despite missing seven games with a sprained MCL. PFF's player rankings have gained a lot of traction in the industry, and for good reason, so there was general agreement that Kelly had gone too far in his quest to recreate the Eagles in his own image.

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While I'm not disputing PFF's player rankings in a general sense, I have a slight quibble with their evaluation of Mathis.

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“Evan Mathis has been a guy PFF has championed for years, right back to his time as a backup guard with the Bengals,” PFF's Sam Monson told me via email. “Why? Because he has never done anything other than play excellent football. When he was locked in an unusual rotating position with the Bengals, he consistently out-graded the starter, Nate Livings. When he finally got his shot to start in Philadelphia, he set about playing like the best guard in football.

“Over the past four seasons, he has graded first, first, first and second in the PFF guard rankings. That second overall ranking in 2014 he achieved in nine games after his injury. Over his four seasons with the Eagles, he was downgraded once every 16.4 snaps as a run blocker.

“​PFF isn’t the gospel of football, and certain schemes will like Mathis more than others, but the bottom line is that he is consistently one of the best performers in the game in the trenches and despite his age is showing no signs of slowing down.”

A fair enough assessment, but I hadn't quite seen Mathis's game that way, at least of late. Based on the tape I watched from last season, which comprised the games against Jacksonville in Week 1, Seattle in Week 14 and Dallas in Weeks 13 and 15, I wondered if Mathis will play at the level PFF presents into the future.

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​I also asked Bleacher Report's Mike Tanier, an Eagles expert and an old Football Outsiders colleague of mine. Mike's evaluation ran more in line with my own:

“Mathis wins as a run blocker when he uses initial quickness to get great positioning on his defender and pin him away from the play. The Eagles' system helps in this regard: Mathis is usually firing off the ball without a huddle against a defender who had to hustle to get into position. Mathis handles his assignments well on inside zone plays, where he can use his experience to peel off double teams to the second level. In pass protection, he has wily veteran 'find-a-way' skills. A defender may beat him off the snap or overpower him, but Mathis will find a way to ride him away from the quarterback. Again, scheme helps here, as the Eagles' pocket is often rolling, and Mathis can give a pass rusher a wide berth to the right if the quarterback is rolling left.

“Mathis is disciplined and crafty enough to be a stabilizer at guard. There's a horizon coming where he won't be able to make up for his lack of brute strength or top athleticism with positioning and orneriness."

I was writing up my own unvarnished opinion when a funny thing happened.

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I tweeted out a preview to this piece on Wednesday, and Mathis contacted me. We started a dialog, and I asked if he would be willing to respond to the five plays presented below with his own thoughts. So, what you'll see here is my take on those five plays, followed by his responses. Those of us who grind tape all the time, even if we know the player responsibilities and understand the playbook, don't know the random elements of particular plays unless we're told.

Mathis asked me to specify that I was digging for negative plays for this piece, which is true. In trying to present a total picture of a player who has earned a reputation for stellar play, I wanted to unearth the less impressive stuff and see if it indicates a larger problem. And while I think there are issues worth addressing, Mathis's responses do present a different picture.

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Here's the sack Mathis gave up to underrated Jaguars pass rusher Ryan Davis in Week 1. With 13:38 left in the first half, Davis lined up between Mathis and left tackle Jason Peters, and simply rode Mathis's outside shoulder to quarterback Nick Foles for the takedown. Mathis couldn't seal the edge and wall Davis off, and that's what you want an elite guard to do.

Mathis: "I hate giving up sacks and haven’t given up too many in my career. This one was a weird one. The play before, I pulled outside and tried to cut the linebacker but ended up just clipping his knee with my head. I ended up with a killer stinger and noticed my entire left arm was numb when I got in my stance. I set back on Davis and punched but had no power. It caught me by surprise and I didn’t adjust well. I should have grabbed him with my right arm and dug my feet into the ground. I had the doctor working on my neck, shoulder, nerve, etc. after this series and not long after this I tore my MCL off the femur. It was such a fun day."

[daily_cut.nfl]Yikes. The next play came in Week 13 against the Cowboys with 6:09 left in the first quarter. LeSean McCoy gains 19 yards on a really nice pull to the right side, but I had a question about Mathis's assignment. He headed up to the second level, where Rolando McClain was chasing running back LeSean McCoy, and Mathis went right past McClain, only to recover and block him out. Tight end Brent Celek was blocking safety Barry Church playside at the second level, so I was curious about Mathis's assignment—this looks like a whiff to people who watch it and don't know the playbook. Why, in a case like this, does the left guard not simply take McClain out of the play right away?

Mathis: "This is a wide, outside play away from my side and my responsibility is to block McClain. Football is a game of angles. When heading up to linebacker level for an outside play, if I was to run where the linebacker was, I’d likely get out-leveraged and not make the block. Instead, I’m aiming where he’s going to be so that I can meet him there. The backer in this case came downhill too fast likely because he didn’t recognize that it was an outside play. This didn’t mesh with my angle that was expecting him to be running flat outside fast. He makes my job easy due to his poor angle, so I’m able to turn back on him and push him off course a little more -- and he has no chance to impact the play."

This play happened with 10:18 left in the second quarter in the Week 13 Dallas game. There's an unbalanced line to the left side, with right tackle Lane Johnson between Mathis and Peters. Johnson takes tackle Nick Hayden at the snap. Mathis fires out to the left edge to block Jeremy Mincey, who loses his footing for a second as Peters chips him, and bounces off Mathis's initial block to take McCoy down for a six-yard loss. It looked like Mathis was talking to Johnson right after the play was over. Was this an assignment issue?

Mathis: "The ball actually is supposed to hit inside of my block. Shady felt the pressure from the opposite defensive tackle, and tried to bounce it outside."

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Teams would frequently run end-tackle stunts against Peters and Mathis on the left side of the line. Against the Cowboys in Week 15 with 2:17 left in the first quarter, Mathis has to double defensive tackle Tyrone Crawford (98) and then peel off to take end Jeremy Mincey inside. Center Jason Kelce is busy dealing with tackle Nick Hayden because right guard Andrew Gardner took linebacker Rolando McClain on a blitz. Mathis looked to be late coming off the peel block on Mincey, and Mincey took Mark Sanchez down for the sack. What was the deal here?

Mathis: "Peters wasn’t doubling with me on the snap, he set and read the stunt and tried to bang it back. I was just late on this one and ended up with poor angle on Mincey, who did a great job coming around fast and strong."

The last play under scrutiny came with 4:48 left in the first quarter of the Eagles' Week 14 game against the Seahawks. Here, LeSean McCoy takes the handoff and makes a jump cut to the right side, but defensive tackle Tony McDaniel throws Mathis to the ground, and McCoy is stopped for a short gain. I was aghast at the fact that a top-tier guard could be thrown down like that, but Mathis advised me to look at the bigger picture.

Mathis: "It’s fourth-and-1, so I’m trying to get my head inside and get a strong initial push. He’s able to shed me and get the assist, but he didn’t get any penetration and has no upfield momentum. Now we’re first-and-goal on the 3.

So, where does Evan Mathis fit in today's NFL? It's my opinion that teams with a zone-blocking system with a lot of slide protection and combo blocks could benefit from his quickness and ability to hit blocks at the second level. I'm less sure about the future of his power game given what I saw, but the subject of this tape piece made it very clear to me that his 2015 tape will tell a different story. He's earnest and motivated, and whether he gets the money he desires or not, I have little doubt regarding his future effort.

"My body of work was limited last year due to the injury," Mathis concluded. "I’m very much ready to come back strong for an entire season and have my best year yet. I’ll listen to the age talk when I lose a step."

And that's where we'll leave it—until the season begins, and Mathis gets a chance to prove his point with a new team.