BOULDER - Jon Embree is making good on his spring promise to give Colorado's newcomers a thorough preseason look - but they'd better show their stuff quickly.

At the conclusion of Day One of his first preseason camp as the Buffs' head coach, Embree said it was still his intention to "evaluate the younger guys in the first few practices and see who can contribute and help early."

By the weekend of Aug. 20, however, the evaluation and experimentation likely will be winding down.

"When we come out of that second scrimmage (the first is Aug. 13, the second Aug. 19), we have to know," Embree said. "That's 13 practices, something like that. Obviously, when we're doing walk-throughs, it helps us see who can learn. We do the walk-throughs in the morning, do some of this in practice and do a little bit of teaching so we can find out who can learn (quickly) and get a grasp of things."

Then, Embree wants the youngsters' walk-through knowledge taken into practice.

Following the weekend of Aug. 20, the Buffs will have nine practices (including a closed scrimmage) remaining before their Sept. 3 opener at Hawaii. Coaches usually want at least that long to give their first and second units most of the practice "reps" before beginning play.

Of the newcomers on the first day of practice, Embree said, "There are some guys out there who looked good and started to pick up some things. The next phase is when you get the pads on . . . see what they do when they get hit."

In general, he described Thursday's work as showing "a lot of carryover from what we did in the spring. The ones - the older guys - got it figured out. The younger guys made some mistakes in there, but this is also their first time. I felt like there was a really good tempo practice."

Senior quarterback Tyler Hansen agreed - at least on the tempo part: "Yeah, the tempo was good, but on the whole it was an average day. We made too many mistakes. But I guess if you're going to make mistakes, the first day is the time to do it."

SINGLE-DIGIT DUDES: There's an adage in football that says, "Low man wins." Think that carries into jersey numbers? Hmmm . . .

Several returning Buffs have changed numbers, most of them going from high to low in the numerals they'll wear this season. To wit:

Junior linebacker Doug Rippy was No. 51, now he's No. 3; sophomore defensive end Chidera Uzo-Diribe was No. 96, now he's No. 9; senior safety Anthony Perkins was No. 46, now he's No. 7; sophomore linebacker Derrick Webb was No. 56, now he's No. 5.

On the offensive side, sophomore receiver Paul Richardson went from No. 80 to No. 6 and redshirt freshman receiver Keenan Canty went from No. 31 to 4.

ONE-ARMED BANDIT: Defensive coordinator/secondary coach Greg Brown has his right arm in a sling and an accompanying protective contraption while he recuperates from surgery to mend a torn biceps.

He suffered the injury earlier this summer trying to hit a pitch thrown by one of his daughters. She threw it harder than he expected, he tried to get a bit too much wood (or maybe aluminum) on it.

It was a freak deal, and Brown "knew something was wrong when I swung."

After the diagnosis and with a short window to have surgery, Brown had to interrupt a vacation to Hilton Head to fly back to Colorado for the operation.

He should be able to shed the sling and the other thing soon. After that, he'll likely stay away from the small ball.

CUTTING THEM DOWN TO SIZE:  With redshirt freshman Cordary Allen (6-1, 235) switching from tailback to tight end, Eric Bieniemy's running back corps now lists true freshman Malcolm Creer (5-11, 205) as its big guy.

Bieniemy's other TBs are senior Rodney Stewart (5-6, 175), senior Brian Lockridge (5-7, 180), redshirt freshman Tony Jones (5-6, 175) and sophomore Josh Ford (5-9, 195).

It was (jokingly) suggested on the practice field that Bieniemy "just wants to see eye-to-eye" with all of his tailbacks. He played on CU's 1990 National Championship team at 5-7, 195 and finished his career as the school's leading rusher.

Good things come in small packages . . .

Embree said Allen's switch was the result of a "logjam at running back . . . and with his big body we thought he might have a chance to do some things at the tight end position. It's similar with what you do at fullback and he should have some knowledge of what we're asking him to do. We feel like it's a chance for him to help us."

WELCOME, TRANSFERS: CU's roster lists four transfers, and while no long-term evaluation can be based on one day of practice, this foursome bears watching.

Senior punter Mark Brundage, who graduated from Rice in four years, is taking advantage of an NCAA rule that allows an unrecruited, non-scholarship player to transfer and play without sitting out the standard one year. Brundage punted for the Owls in 2008-09, but sat out last season. His net average in 2009 was a respectable 41.8 yards.

Senior receiver Logan Gray, a four-year Georgia graduate who enrolled in summer graduate school classes at CU, also is eligible due to an NCAA rule that allows him to switch schools and play immediately because his original school didn't offer the post-grad degree of his choice. The athletic Gray (6-2, 190) lettered three years at UGA, moving from quarterback to receiver as a junior.

Junior defensive back Makiri Pugh (5-11, 190) is a traditional transfer - also from Georgia - and sat out last season. Freshman center Brad Cotner (6-4, 290) arrived from Ventura (Calif.) Community College.

TYLER TO TYLER? Among the newcomers debuting Thursday afternoon was freshman Tyler McCulloch, a 6-5, 205-pound receiver from Albuquerque. He was a late 2011 signee, making it official with CU on Valentine's Day.

After a wobbly start Thursday, McCulloch made a couple of acrobatic receptions that got the defense's attention.

"I came out a little too excited, but once I settled down I started catching some balls," he said. "But I've still got a long ways to go."

Embree declined to push too much praise in McCulloch's - or any freshman's - direction. "It's Day One," he said. "Anybody can do something once . . . ask me on Saturday and I'll start putting some guys' names out there. There are some freshmen I'll be excited to see when we put the pads on."

That will happen Monday morning (8:30-11 a.m.).

BUFF BITS:  Embree confirmed that junior offensive lineman Bryce Givens would not return to the team. "That ship's sailed," he said. "It was a long, long, long, long shot (of Givens returning) . . . . Finding a pair of starting cornerbacks is a camp priority. On Day One, a parade of candidates rolled through both sides, including senior Travis Sandersfeld and sophomore Parker Orms - both of whom previously played safety. Embree said both performed well at corner, as did sophomore Ayodeji Olatoye (formerly Deji) and freshmen Kyle Washington, Greg Henderson and Sherrard Harrington. "It was good competition," Embree said. "We got three or four picks and no dropped interceptions - that's good, too. Those guys did well." . . . . Orms left practice early with a cramped calf . . . . The Buffs have another morning walk-through on Friday (6:30-7:30 a.m., closed to the public), then practice again in the afternoon (5:30-8:30 p.m., open to the public) . . . . The first day of fall classes is Monday, Aug. 22. Practices will be open until that afternoon's work.

Contact: BG.Brooks@Colorado.EDU