Bruce Irvin and Shea McClellin personify the struggles of some rookie pass-rushers

For some collegiate defenders, the move from the NCAA to the NFL is as easy as falling off a log and breaking a quarterback in half on the way down. Quinton Coples, taken 16th overall in the 2012 NFL Draft, finished his first preseason with 4.5 sacks, and the former North Carolina star recently admitted that he's still getting winded as he gets used to the speed of the pro game. Chandler Jones looks like the young pass-rusher Bill Belichick has desired for most of the last decade. Houston's Whitney Mercilus seems to be a natural in Wade Phillips' multiple fronts, and Melvin Ingram -- the man I believe to be the best overall defender in the 2012 draft class -- is already confusing opponents with his rare ability to play all over the front for the San Diego Chargers.

For other potential pass-rushers, however, the move to a higher rent class isn't so simple.

A higher altitude for the Mountaineer

With 4:39 left in the third quarter of the Seattle Seahawks' 21-3 win over the Oakland Raiders last Thursday, rookie defensive end Bruce Irvin finally sacked an NFL quarterback. It was a combined sack with cornerback Byron Maxwell, and Irvin looped inside the right tackle to get to Terrelle Pryor. Four plays later, Irvin shot through the defensive left side and caused a Pryor incompletion by hitting him just as the quarterback released the ball. And with 9:13 left in the game, Irvin contained Pryor as he was rolling right to record the first solo sack of his NFL career. Irvin's 1.5 sacks and three quarterback hits in the game won't count on the official stat sheets as this was a preseason game, but the production certainly counted to Irvin -- the 15th overall pick in the 2012 NFL draft hadn't registered a sack or tackle in the previous three games.

Playing frequently in a 3-3-5 stack defense at West Virginia, Irvin relied on raw speed to get around tackles and shoot gaps when he was inexplicably asked to play inside the tackles and deal with double-teams consisting of blockers who outweighed him by 80 pounds. He never developed the moves required to succeed as a pass-rusher at the NFL level -- the inside counter and spin move most specifically -- and when the Seahawks selected him earlier than most expected Irvin to go, everyone knew there would be a transition period.

"Well, he's frustrated." Seahawks head coach Pete Carroll said of Irvin the day before that Raiders game. "He's frustrated with how hard it is to get sacks, but these last two days in particular he's just looked terrific in practice. What we're trying to do is make sure we give him plenty of opportunity to take advantage of his speed. That means he has to get his quality rushes on the edge to show that. That's not to show him off, it's to utilize him. So we're trying to make sure that we get that done.

"He's playing exactly like we hoped; he is going to be in all of the sub-packages. He actually had his best day of practice yesterday and the day before that was an excellent day too. What that means is he's now taking advantage of the calls, and what's asked of him, with great speed. He was thinking a lot and trying to put things together and it wasn't as natural as he would become. He's getting a lot closer. He's going to get better throughout the season; he just does not have a lot of experience behind him."

Carroll also said that Irvin was close to four sacks in the Week 3 game against Kansas City, but he came away with no quarterback hits and no tackles for the third straight week, despite the fact that he was on the field for 53 percent of Seattle's defensive snaps against the Denver Broncos and 53 percent against the Chiefs. One of the reasons Irvin was finally able to cut loose against the Raiders was that no defensive player was on the field for Seattle more than the rookie -- he was active on 91 percent of the snaps.

In football, repetition facilitates understanding. For players like Irvin, few things are more important, especially given the multiple roles he and other edge defenders are often asked to play in the NCAA.

Gruden: Assignments can confuse the issue

"A lot of college players, if you really study the game, they never really get a chance to unleash the pass rush," ESPN's Jon Gruden told me in a media conference call this week. "There's a lot of third down and eights and nines where you're seeing a standard drop-back attack. You are seeing spread offenses. You are seeing options from third-and-7.

"So, a lot of defensive linemen, they have multiple assignments with defending the option, their different assignments, [and] the hash marks are different. They have field blitzes and boundary blitzes, and the amount of time where they can become specialized rushers is minimized with the 20‑hour per week schedule and the kind of games they play. You might play against a wishbone one week, and you might play against a no‑huddle spread attack the next. You don't get a lot of time and individual work to really polish your pass rush. So I think those are a couple reasons why some men might struggle initially. When you come to the NFL, if you watch the great rushers, they play right end, they play left end and they stand in multiple stances."

We're not in Boise anymore...

For Chicago's Shea McClellin, the challenges are different, but no less daunting. McClellin ranked 48th in this year's Shutdown 50 because he was a volatile, dynamic moveable chess piece at Boise State. He screamed off the snap in a "wide-nine" set, and made plays all over the field as an outside linebacker. But when asked to face offensive tackles straight up, McClellin's lack of upper-body strength in relation to other defensive ends was evident. When the Chicago Bears selected him with the 19th overall pick in the 2012 draft and moved him to end in their four-man fronts, Chicago executives and coaches knew that an adjustment period, similar to the one Irvin would have, would be necessary.

In practices, McClellin struggled to get free against Bears tackles J'Marcus Webb and Chris Williams, neither of whom would be on anybody's "NFL World-Beaters" list. As he told Sean Jensen of the Chicago Sun-Times, a new reality set in early.

"Early on, I was very frustrated," McClellin told Jensen. "Then I was pressing ... Coach [defensive coordinator Rod] Marinelli told me to relax a little bit and just go out and have fun. I've been trying to do that. Even if I'm not 'winning,' as long as I'm giving 110 percent, that's all I can do."

McClellin won in his first preseason game, when he was stumped off the defensive left edge against the Denver Broncos, adjusted to read run up the middle, and adjusted again to run down Denver backup Caleb Hanie for a sack.

"I was trying to take a good angle to get him," McClellin said. "Then using that relentless mentality."

But through games against the Washington Redskins, New York Giants, and Cleveland Browns, McClellin's productivity dropped as his reps did. He had no sacks or quarterback hits against the Redskins despite his presence on the field for almost half the snaps, got one tackle for loss against the Giants while appearing in just one out of four possible plays, and didn't see the field at all against the Cleveland Browns in the preseason finale.

Bears head coach Lovie Smith believes that McClellin will push through the transitions, but understands that there will be some false steps at first. In the end, the Bears would like McClellin to allow the perennially underrated Israel Idonije to move around the line while the rookie provides burst in sub-packages.

"I want them to put as much pressure and be miserable early, as a rookie coming in, because of the standard that you set for yourself right away," Smith said of the pressure first-round picks generally put on themselves."That's what Shea did. You want him to say, 'I've got to get better. That wasn't good enough.'"

New Bears general manager Phil Emery was the one who sifted through all the draft-eligible pass-rushers to find the one guy who would be the perfect complement to Julius Peppers. Deciding on McClellin, Emery said, was an easy thing to do.

"We made it an equal, not competition, but an equal evaluation," Emery said. "We had them put it all together. Then, as a scouting staff, [we] went through those players. This guy is made of the right stuff. He's got a very high motor, and he's a very good, earnest, hard-working player who is going to fit in any locker room.

"You have other players in the mix, and we had seven players around that pick. But he was the player that was at the top, and we made that move forward."

Smith has seen enough to believe that the Bears have their man in the rookie. " 'He can't play the run. He's too small. He's this, he's that,' " Smith said, recalling criticisms of McClellin. "But he's a perfect complement for Julius Peppers when they start running from the big dog to him. We've been saying all along, 'He's right on time.'"

The regular season is right around the corner, which means double-time for those NFL players whose college training left them short in certain specifics at their new position. Bruce Irvin and Shea McClellin will now face the work required when busting the curve.