A sixth-round pick, Danny Trevathan played the second-most snaps on the Broncos defense this season. (Dilip Vishwanat/Getty Images)

JERSEY CITY, N.J. -- That Danny Trevathan -- 6-feet-and-change and about 235 pounds -- was smaller than the ideal NFL linebacker came as no surprise to scouts prior to the 2012 draft. But there was another issue.

Trevathan was slow.

He did not run the 40 at the combine, then posted a lumbering 4.82-second time during Kentucky's Pro Day. That's a time equal to the marks put up that year by QB Kellen Moore, 300-pound defensive tackle Kendall Reyes and Auburn center Josh Harris, among others.

Trevethan had just wrapped a college career that included 144 tackles in 2010 and 143 in '11, the latter of which landed him onSports Illustrated's All-America Team, alongside Lavonte David and Manti Te'o. And suddenly, that barely mattered. Drafting a linebacker who is either too short or too slow is one thing. Taking a guy who fell into both categories? Almost unthinkable.

But at least for Denver linebackers coach Richard Smith, Trevathan's performances at the combine and Pro Day did not mesh with the player Kentucky had trotted out on the field for four seasons. So he decided to check in with Trevathan one more time.

"Are you faster than that 40 time?" Smith asked.

"Yeah," Trevathan responded. "I had a pulled hamstring. ... When I'm healthy, I'm a 4.45 guy."

"Oh, come on," a hesitant Smith said. "Don't be kidding me."

"Give me another opportunity, and I'll run a 4.4 for you."

The Broncos provided Trevathan with that second chance and then some, after stopping his slide through the draft in Round 6. Trevathan's story could have become a footnote there -- the selection Denver used on him, No. 188 overall, was one of the picks acquired by trading Tim Tebow to the Jets.

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Instead, he worked his way into Denver's rotation during his rookie season, before making the coaching staff another promise headed into 2013.

"I told them, 'I hope you're ready for the person I'm going to come back as,'" Trevathan recalled. "They said, 'I hope you're not just talk.'"

He wasn't.

"He came back as just a totally different-looking guy," said Smith of Trevathan's offseason metamorphosis to a player more capable of handling the NFL's rigorous schedule. "But don't give [playing time] to them, they have to earn it. Over time, as you kept watching him work and watching him compete, he earned that right."

Trevathan's first game as a Broncos starter, in the NFL's season-opening showcase game between Denver and Baltimore, threatened to unhinge all of his progress. With the Broncos en route to a blowout victory, Trevathan stepped in front of a Joe Flacco pass and appeared headed to the end zone for a pick-six.

He made it across the goal line. The football did not.

Trevathan started his celebration early and let go of the ball inches shy of the end zone. When he reached the sideline, all Trevathan could do was apologize.

"That was definitely a sign that let everybody know that he's maturing," Wesley Woodyard said. "He came back strong, and he hasn't looked back since. He's a fighter, he loves this game."

Even though Seattle wide receiver Golden Tate had no opinion of Trevathan when he was asked about him this week -- "It's just another guy," Tate said -- the Broncos likely would not be here without their former draft steal. Trevathan played 963 defensive snaps this season, per Pro Football Focus, which ranked as No. 2 on the Broncos behind now-injured cornerback Chris Harris; no other linebacker was on the field for more than the 765 snaps from Wesley Woodyard.

It was an injury to Woodyard, also a Kentucky football product, that opened the door for Trevathan to take over play-calling duties. Sunday, Trevathan will find himself with his usual plethora of responsibilities, from trying to slow down Marshawn Lynch to checking Seattle's tight ends in coverage.

"Danny's best attribute is he's very instinctive," said Smith, who compared Trevathan to former NFL linebacker Jamie Winborn, a member of seven different franchises from 2001-10. "Really good cover skills -- we can match him on a tight end or running back. He has things you can't coach: speed, quickness and instincts."

Said Denver head coach Jack Del Rio: "I think Danny Trevathan is the kind of a guy who’s ascending and has really become a strong player for us. Because of this season, I would call him an emerging player. Very productive, very instinctive. I think he’s got a very bright future."

Based on his draft position alone, Trevathan's rise from a possible special-teams player to a depth guy on the linebacking chart to an irreplaceable member of this Denver defense could fall under the banner of a complete surprise. Woodyard, for one, expected it.

"I was never surprised to see him play as good as he's playing," Woodyard said. "I watched Danny in college and once he got here, he's just accepted his mode. He's continued to become a bigger and better man on the field and off the field."