Jim Mora says UCLA will need a number of players to replace injured Myles Jack

In losing Myles Jack, the UCLA defense lost more than just a hard-hitting linebacker.

Jack’s skill set allowed him to be a force against the run and also to blanket receivers and backs in pass coverage.

With him on patrol, the Bruins did not have to worry about changing personnel based on whether they faced a run or pass situation.

“We’ve been able to play one personnel group against any offensive group, whether it has been two backs, a tight end, two wide receivers or one back and four wide outs,” UCLA Coach Jim Mora said.

Without Jack? “That will be a little more difficult,” Mora said.

Arizona runs an up-tempo spread offense, which seeks to create and exploit mismatches.

“They don’t give you a lot of formations or personnel groups, but boy they go fast,” Mora said.

And that’s the problem.

UCLA will require a handful of players to replace Jack. Defensive backs Ishmael Adams and Tahaan Goodman and linebackers Cameron Judge and Aaron Wallace are in that mix.

Getting the proper personnel package on the field becomes the challenge.

“If they substitute, then we have a chance to substitute,” Mora said. “Now, they don’t substitute a lot, but if they do, then we have to be ready to substitute. If they get first down, you have to be ready to get a guy in with the clock stoppage.

“If you get stuck with the wrong people on the field — which happens in every game — then you have to be ready to play and hold up for a down.”

Injury explanation

Jack sustained a torn meniscus in his knee during a non-contact, seven-on-seven passing drill Tuesday.

There typically are three options to repairing meniscus, Mora said.

“You can snip the meniscus, get it out of the joint; that was not a possibility,” Mora said. “You can let it go; that was not a possibility. The third thing, if it’s a significant tear, you have to stitch it. That elongates the recovery time.”

Mora said Jack’s recovery would take between four and six months.

Asked whether there was any chance Jack could get back for a bowl game or sooner, Mora said, “If he could, that would be a bonus. We’re not really counting on it. That wouldn’t be fair to put that kind of pressure on him. I’m certain he is out for the year.”

Happy return

Receiver Devin Fuller knew the answers before the questions were complete.

His 56-yard punt return against Brigham Young nearly broke a 10-year drought. The Bruins have gone 128 games and returned 254 kicks since a UCLA player took a punt to the end zone.

That was …

“Maurice Jones-Drew,” Fuller said.

In …

“2005,” Fuller said.

It came against California, which was the only fact Fuller didn’t know.

But he was plenty satisfied with his return, which set the Bruins up on the 17-yard line. Five Paul Perkins carries later and UCLA had the touchdown that tied the score, 10-10.

After the return, Fuller said, “I could see our sideline get amped up. I felt a little more life than there was before. That’s my role; make a play for this team.”

chris.foster@latimes.com

Twitter: @cfosterlatimes