MOBILE, Ala. --Although the Senior Bowl game Saturday caps the week, it's all about practice for player evaluation. The on-field work for 110 players representing North and South teams began here Tuesday afternoon in front of audiences of over 1,000 scouts, media representatives and draftniks.

Two players from Colorado universities accepted invitations, both from Colorado State: quarterback Garrett Grayson and offensive lineman Ty Sambrailo.

The day wasn't easy for Sambrailo. At times, the 6-foot-6, 309-pound Sambrailo looked tentative, as though trying to figure out where to go. But any struggles must be chalked up to working at right tackle, a position he last manned in 2012 before becoming the Rams' full-time left tackle in 2013.

"I thought I was a little shaky," he said. "It's been a couple of years since I played right tackle with live reps, and coming out here and playing agains the best in the country is an interesting way to get back into it.

"There's a lot of areas I need to get better at, but I thought overall it wasn't too bad."

But as the Broncos saw with Chris Clark last season, going from one side to the other isn't as simple as it sounds.

"It's kind of like writing right-handed for your whole life, and then switching over and writing left-handed," Sambrailo said. "It doesn't seem like much, but you know there's little differences that make it tough."

… The receiving star of the day was Duke's Jamison Crowder.

As the smallest receiver at this year's Senior Bowl, you expect him to have success in the slot. But one of the best plays he made was working outside in the one-on-one drills against CBQuinten Rollins of Miami (Ohio). With Rollins pressed near the line of scrimmage, Crowder blew past him and had two steps of separation, more than enough to make the deep, over-the-shoulder grab up the right sideline.

Crowder was the complete package Tuesday. His cuts were precise and sharp. He flourished at drills in which he caught the ball near the sideline, expertly getting both feet in bounds.

Just as good as the performance was his measurements. Unlike some other players, Crowder didn't lose inches or pounds relative to his listed size when he weighed in; the 5-foot-8, 174-pound figures offered by Duke were accurate. (Compare that with Stanford WR Ty Montgomery, who checked in 2.4 inches below his previously listed 6-foot-2 size.) And although Crowder is the shortest and lightest receiver here, others have smaller hands and a shorter wingspan.

… Rollins did a nice job of recovering from his early struggles. Possibly the most athletic cornerback in Mobile, he didn't play at Miami until last fall, playing four seasons on the basketball team. He is raw, but fluid and can be aggressive against the run. His need for polish means he probably won't contribute much as a rookie, but he has massive upside for a team with patience …

… The non-FBS players always bear monitoring here because of the caliber of competition they now face, so I had my eyes on Tennessee State offensive lineman Robert Myers (6-5, 329).

At this point, Myers has the size, but not the technique, and was susceptible to attack from the inside. Iowa defensive tackle Carl Davis exposed Myers' inability to get into his stance fast enough, driving through him and pushing him backward during a one-on-one drill. In fairness, Davis made a lot of offensive linemen look bad, and used his 34.5-inch arms and 321-pound frame to get consistent push throughout the North team's practice.

Later in the one-on-one period, Myers established too wide of a stance and nearly lost his balance, but showed his natural strength by holding off Arizona State's Marcus Hardison …

… Washington LB Hau'oli Kikaha is a good edge rusher, but that might be all. When asked to work in coverage, he struggled, both in zone during the team period and in one-on-one work, when he had difficulty dropping back and changing direction, showing stiffness which allowed tight ends to easily get past him. This might limit him to sub-package, edge-rushing work.

But Kikaha's teammate, defensive tackle Danny Shelton, was one of the most impressive players in either practice. If you're looking for a big body who can attack off the snap and has enough interior pass-rush punch to draw double teams and leave the edge rushers with one-on-one battles, the 343-pound Shelton is the guy ...

… The biggest question for Baylor quarterback Bryce Petty involves his transition out of the up-tempo, shotgun-based offense he ran at college into a game that requires at least some work from under center and with a huddle, depending on the scheme his next team utilizes. His first day was promising, given the nature of his adjustment.

I'll touch on Grayson more following Wednesday's practices, but a good sign from the body measurements was his hand size -- at 10 1/4 inches, it is the largest of the quarterbacks here. Although he doesn't yet have timing with the receivers he just met this week, he throws a good deep ball and reads his keys well, although a floated pass that Mississippi safety Cody Prewitt picked off marred his day.

With Oregon's Marcus Mariota and UCLA's Brett Hundley declining to participate, Petty and Grayson are the best quarterbacks here -- and could be fighting to be the third quarterback off the draft board in May. Hundley was the only quarterback listed among the nine players called out by Senior Bowl executive director Phil Savage for being invited but not participating -- and not contacting the Senior Bowl to formally decline the invitation.

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