Redshirt freshman quarterback Nick Hirschman is likely to make his first college start for Colorado this week at Arizona State, replacing injured starter Tyler Hansen.

Hirschman has taken the majority of the first-team practice repetitions in the first three practices of the week and coach Jon Embree is generally reluctant to play someone who hasn't participate fully in practice by Wednesday.

Hansen, who suffered a concussion that knocked him out of last week's home loss to Oregon, was at Wednesday's practice but was not in pads with his teammates. He has started every game so far this season.

Embree was coy when asked for an update on Hansen's status.

Nick Hirschman is sacked by Dewitt Stuckey of Oregon in the second half of the Buff loss.For more photos of the game, go to www.dailycamera.com.October 22,
Nick Hirschman is sacked by Dewitt Stuckey of Oregon in the second half of the Buff loss. For more photos of the game, go to www.dailycamera.com. October 22, 2011 / Cliff Grassmick ( Cliff Grassmick )

"That I don't know," Embree said. "We'll have to see. You'll have to tune in."

If Hirschman starts Saturday, it will mark the fourth consecutive season and the eighth time in the past nine years the Buffs will have used at least two starting quarterbacks.

The only season during that span in which the starter remained the same throughout the year was the 2007 season when the Buffs finished the regular season 6-6 with Cody Hawkins under center and lost to Alabama in the Independence Bowl.

Hirschman has played in each of the past three games, seeing limited action in road losses at Stanford and Washington and playing more than a half against the Ducks.

Hansen's 2010 season ended prematurely in Week 7 when he suffered a spleen injury against Texas Tech.

Kasa moving?

Junior defensive end Nick Kasa could be considering a move to tight end.

Kasa was wearing a black No. 90 jersey (offense) at Wednesday's practice and stayed after to catch passes from quarterback Connor Wood.

Nothing has been announced by the program.

Kasa, a 6-foot-6, 270-pound product of Legacy High School in Broomfield, chose CU over Florida three years ago in recruiting, in part, because Florida coach Urban Meyer wanted to move him to tight end or offensive line.

Kasa has played in all eight games for the CU defense, but he has made just seven total tackles in 132 snaps and hasn't recorded a sack.

Defense needs help

The Colorado defense is among the worst in the nation in several areas, including points allowed and passing defense. The Buffs are allowing 37 points a game and rank 114th in pass efficiency defense.

Injuries and suspensions have contributed to the team's inability to stop opponents, but Embree also blamed the offense this week.

"We are not doing a good enough job offensively limiting the exposure of our defense," Embree said. "I never realized how hard it is to play defense until I had to coach it for four years and it is amazing how much running and how the intensity level is totally different on that side of the ball, and you can only do it so many times a game effectively.

"The more you are exposed, the less effective you are on that side. That is where the offense comes in and that is where we have to be better offensively in helping our defense."

The CU offense ranks 113th in rushing, 102nd in total offense and 107th in scoring.

Big boost

The CU secondary will get a big boost this week with the return of free safety Ray Polk, who missed last week with a concussion, and senior cornerback Travis Sandersfeld, who has missed the six games after sustaining a lower leg injury against Cal in Week 2.

Sandersfeld was named a starter at cornerback in fall camp and played well in the first two games against Hawaii and Cal.

Polk is one of a handful of Buffs who will be returning home on the trip to Arizona. Polk was recruited to CU from Brophy Prep in Scottsdale, Ariz.

"Polk's going home," Embree said. "I knew he wasn't going to miss this game."

Notable

Defensive back D.D. Goodson practiced Wednesday and will likely be available against ASU after suffering a concussion against Oregon. ...

The Buffs practiced in the bubble for the first time this season after snow fell Tuesday night and into Wednesday. "It went all right," Embree said. "We're practicing differently anyway, so it works out good from a space standpoint because we're going more good on good and doing individual work and stuff. It went good."