LOS ANGELES -- A tweak here, a contusion there; This guy has a strain and that one has a sprain. Pretty soon the minor injuries start mounting to the point where it looks as if it might be a concern.

UCLA's football roster seems to have reached that point after seven spring practices. A total of 24 players did not dress for practice Tuesday and then receiver Jerry Johnson, cornerback Aaron Hester and safeties Librado Barocio and Anthony Thompson joined the walking wounded by day's end.

That's nearly one third of UCLA's current roster sidelined because of injuries. Most of them are minor -- coach Jim Mora likes to say they are "tweaks" or "he did something to his [insert body part here]" -- but it still seems a fairly alarming number. Unless you're the head coach, that is.

"I’m concerned only with the guys that are practicing," Mora said. "Those other guys who are over there, it’s like I don’t even see them."

Mora is trying to instill a heightened toughness in the team. Practices have been grueling so far with a constant aura of physicality hovering over every drill and a tempo that has just about everybody winded by day's end.

The pace and the hard hitting have taken a toll, but the fact that injured guys don't matter to Mora is part of the new attitude and the players don't seem to mind.

"We're building a new mentality out here," linebacker Eric Kendricks said. "Everyone is out here busting their butt and if you have a little nick or bruise, maybe last year you sat out but this year you want to push through for your teammates."

Mora said he doesn't pay attention to guys sidelined with minor injuries because he feels as if he has more than enough depth to cover the bases. He spent most of his career in the NFL with roster limits of 54 players. UCLA has 97 players on its spring roster and even with 28 players out, he has 69 in uniform.

"This is like a kid in a candy store to me to have all these players," Mora said.

That could be bad news for players who aren't able to deal with Mora's more demanding expectations. He said last week that he expects there to be a "fail rate" meaning that some players currently in camp will not be around when fall rolls around.

If the defensive backfield takes any of those fail-rate hits, it could be a long season for the UCLA defense. The Bruins are scrambling in the secondary after Barocio and Thompson went down with injuries Tuesday and Hester was limited to non-contact drills because of "concussion-like" symptoms.

The Bruins ended practice Tuesday with only six healthy scholarship defensive backs: cornerbacks Sheldon Price, Anthony Jefferson, Brandon Sermons (playing with a cast on his hand) and freshman Marcus Rios and safeties Tevin McDonald and Stan McKay.

Safeties Dietrich Riley and Alex Mascarenas were ruled out for spring practice and safety Andrew Abbott had knee surgery last week and is unlikely to return before the end of spring.

"We have some issues so it’s a juggling act right now to keep guys healthy and keep them on their feet," defensive backs coach Demetrice Martin said. "The positive thing is that everybody gets to learn every position. We’re rotating guys around and some guys are playing nickel and some guys are playing corner, safety so they are learning the defense from every aspect of the secondary and that can’t do anything but make us stronger in the end."

Dalton Hilliard, a safety trying out at running back would seem an obvious choice to help fill out the depth chart. Damien Thigpen, who has switched from cornerback to F-back throughout his career, is another option. The Bruins also have some incoming freshmen -- notably Ishmael Adams -- who could contribute in the fall, but that won't help them now.

"I’m looking up and down our roster trying to find some prospects from within to come on a recruit to the dark side," Martin said.

Martin said he couldn't pinpoint why his unit has been hit so hard by the injury bug, but he knows that Mora's tough-nosed style isn't going to change any time soon and he's just fine with that.

"I only know one way and that’s to go hard," Martin said. "I’m not going to change. Maybe I’ll put the brakes on some guys and be smart, but I only know one way to go."