One of the biggest concerns for the Colorado football program entering spring practices last month was who might step forward to claim two starting cornerback jobs left behind by Jimmy Smith and Jalil Brown, both of whom are headed to the NFL.

With only one practice remaining before the annual spring game Saturday, it's safe to say the program will begin fall camp in four months with the same question at or near the top of the coaching staff's priority list.

Almost all of the contenders have had moments this spring when they have looked capable and up to the challenge. Unfortunately, each also has had moments that have led to coaches scratching their heads in consternation and even a few glorious meltdowns.

Coach Jon Embree said no one has emerged at the position because no one has proved capable of consistency from one day to the next. Defensive coordinator and secondary coach Greg Brown agreed.

Embree said guys aren't playing their best football yet because they aren't comfortable mentally yet. That will come with time and effort.

"To be a good football player you have to know what you can and can't do physically and then make sure that you protect yourself," Embree said. "So if I can't run and I'm a corner, then I need to make sure I'm playing with good technique, using my hands and staying on top. If I can run, then I can be a little bit more aggressive. But when you're just kind of out there waiting to see what's happening trying to react, you don't do anything.

"... No one does it every play yet."

The list of candidates is a long one.It includes veterans such as Jonathan Hawkins and Arthur Jaffee, who have logged their share of playing time on defense and special teams but never have risen to the level of starter.

Transfer Makiri Pugh is another player with a little more experience.

The list also includes a gaggle of young players who have learned behind Smith and Brown for a year or two and now have to prove they can play at a high level -- players such Deji Olatoye, Jered Bell, Paul Vigo and Josh Moten.

Players say their inconsistency is a product of learning new schemes and play calls and how to do things the way Greg Brown wants them done versus what former secondary coach Ashley Ambrose taught them last year.

They say Ambrose and Brown are similar in their methods, which makes sense because Brown mentored Ambrose, but there are subtle differences that can trip up players.

"We're all still in the learning process," Bell said. "We're all young. So that is probably one of the main reasons. We've just got to know our technique and get in the playbook a little more. That will help a lot more on the field."

Bell said Brown asks defensive backs to learn and understand the entire defense, not just their responsibilities. That has extended the learning curve somewhat.

Bell said he came to Colorado to be a starting cornerback and he has every intention of making it happen this year. He logged some limited playing time on defense last year.

"It helped a lot because confidence is a big thing when you're playing corner," Bell said. "So being on the field last year has given me the confidence to come out and do it again, hopefully get a little more playing time and earn a starting spot."

Olatoye admits to his inconsistency, but he also says it's a product of the changes going on in the defense, play calls and techniques. He says he is confident he and several of his teammates will be playing at a higher level by the time fall camp rolls around and even more so once the season arrives.

"Our corners are getting more consistent by the day," Olatoye said. "We have our up and down days, but for the most part we try not to have too many bad plays in a row. It's really about getting in our books and watching film."

Notable

Tight end DaVaughn Thornton returned to the practice fields Tuesday but did not participate. He was taken from the field in an ambulance on Monday after a collision that resulted in upper-back and neck pain. Embree said he doesn't know if he will allow Thornton to participate in the spring game. "He wants to play. We'll just see how it works," Embree said. ...

Toney Clemons has been held out of recent sessions because of a nagging hamstring injury and might not participate in the spring.