Zach Dyer hadn’t made a tackle since his senior year at Olathe South.

Saturday against Colorado, he made eight.

“It’s so much different,” said Dyer, who was KU’s backup quarterback before moving to safety last week. “It’s a different mind-set than quarterback.”

Dyer split time at quarterback with Mario Kinsey last season, making four starts. He started the 2002 season opener at Iowa State but was replaced by junior college transfer Bill Whittemore at halftime and had been relegated to a backup role since.

When coach Mark Mangino asked Dyer if he’d like to switch positions, the fourth-year junior jumped at the chance to get back on the field. He made his debut on special teams last week at Baylor, but didn’t play in the secondary until Saturday in KU’s 53-29 loss to CU.

“It’s tough sitting on the sidelines,” said Dyer, who played on both kickoff teams, the punt-coverage unit and defense Saturday. “That’s about the toughest thing, just sitting out there wanting to be out there on the field.”

Mangino hopes Dyer (6-foot-2, 200 pounds) can bolster a defense that entered the game ranked last in the Big 12 Conference and 112th in the nation in run defense.

“We’re going to put our best players on the field,” Mangino said. “He’s too big, he’s too strong, he’s too quick and he’s too talented to be standing next to me on Saturdays. I would have done it sooner. We took a pretty substantial risk there.”

Whittemore has locked up the job at quarterback with three straight games with more than 300 yards of total offense, but Mangino was reluctant to move Dyer because of KU’s lack of depth at quarterback. Before red-shirt freshman Brian Luke had a cast removed from his injured hand this week, senior Jonas Weatherbie would have been KU’s only backup at quarterback if Dyer had moved.

Dyer had his ups and downs for KU on a day that Colorado rushed for 427 yards and netted 546 total yards.

“Nobody should be able to run the ball the way Colorado did today,” Mangino said. “We should be able to make some more plays, and we will. We’re going to keep working at it.”

So will Dyer. The junior took a few reps at quarterback last week “to stay fresh,” but will now focus his attention on his new roles.

“Once he understands things, he’ll play an important role and be a run stopper for us,” Mangino said. “I’m convinced of that.”

Dyer said he’s “learning on the go” and admits he’ll have to play better to help the defense.

“I think I did OK,” he said. “I missed too many key tackles.”

In the third quarter, CU fullback Brandon Drumm leveled Dyer just as he was closing in on Chris Brown. The tailback sprinted 48 yards, sparking a 77-yard scoring drive.

In the fourth quarter, punter Curtis Ansel pinned the Buffs on their own 2-yard line. Brown, however, broke Dyer’s tackle on first down and scooted 29 yards before being brought down.

“I would have liked to make that tackle,” Dyer said. “I’d love to have that play back. There’s quite a few plays I’d like to have back.”

His teammates, however, expressed confidence in him.

“I knew he could do it,” Whittemore said. “I wasn’t surprised to see him out there. We could use him out there.”

As for Whittemore and the quarterbacks, Mangino said Weatherbie had moved up to No. 2 on the depth chart and Luke was third.