PHILADELPHIA (973espn.com) — Evan Mathis was hardly the only veteran Eagles player who didn't see eye to eye with Chip Kelly and the former Pro Bowl guard, who just won a Super Bowl with the Denver Broncos after being released by the ex-Eagles coach, opened up about his time in Philadelphia in a wide-ranging e-mail interview with Mike Klis of 9NEWS in Denver.

Like a lot of us Mathis honed in on two familiar criticisms of Kelly, the coach's repetitive, one-trick pony of an offense, and his inability to manage certain personalities.

"There were many things that Chip had done that showed me he wasn’t building a championship team," Mathis wrote rather bluntly. "Two of the main issues that concerned me were: 1. A never-evolving, vanilla offense that forced our own defense to play higher than normal play counts. 2. His impatience with certain personality types even when they were blue-chip talents.

"The Broncos team I was on would have eaten Chip alive. I don’t think he could have handled the plethora of large personalities."

Like him or not, it's hard to argue with Mathis' assessment of Kelly.

The now-49ers coach's slavish devotion to tempo means running the same plays over and over, coupled with that disastrous impact on the other side of the football. In two of the three seasons Kelly was leading things in Philadelphia, Bill Davis' defense was on the field more than any other stop unit in the NFL and the only year it wasn't the defense was ranked 31st in a 32-team league.

Kelly's high-profile butting of heads with players like DeSean Jackson and LeSean McCoy was also well-documented with McCoy intimating it was a race issue although to be fair Mathis himself kind of derails that particular charge.

While he went about it in different ways than Jackson or McCoy, the veteran guard has a "big" personality as well and Kelly had a difficult time dealing with him as well so the issue wasn't with race, it was with players who didn't always toe the line.

Mathis, though, did confirm that he asked Kelly to release him after the team refused to renegotiate his deal last offseason, one that would have paid the Alabama native $5.5 million.

"Since I wasn’t going to be paid what I was offered and I wouldn’t simply be given better incentives to play for a coach who wasn’t building a winning team, I decided I wanted out of Philadelphia," Mathis continued.

After reports surfaced in late March that the Eagles would cut Mathis if they couldn't trade him, the veteran texted Kelly a link to the Engelbert Humperdinck video "Please Release Me."

Kelly obliged and Mathis chose a $4 million offer from the powerful Broncos rather than a $5.5 million overture from Miami, a decision that landed the 34-year old the Super Bowl ring he desired and an opportunity to perhaps take the same path as Peyton Manning, retiring on top.

Mathis will be a free agent again in March and is set for ankle surgery so he hasn't yet decided if he wants to play in 2016.

He did, however, offer one-last piece of advice for his old coach.

"I hope Chip learns from his experiences in Philadelphia and grows as a coach," he wrote. "Maybe he’ll find some constructive criticism from this."

-John McMullen covers the Eagles and the NFL for 973ESPN.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen