Attrition has left rising sophomore Randall Goforth as UCLA’s most experienced defensive back.

Tevin McDonald, who had 79 tackles last season, is transferring to Eastern Washington after being dismissed prior to spring camp. Dietrich Riley, who had 36 tackles through eight games in 2011, is unavailable too; already working back from a neck injury, a separated shoulder has left him on the exercise bike.

So here’s Goforth, whose 40 tackles as a freshman were overshadowed by a Twitter impersonator that trash-talked USC players using his name. The 5-foot-10 safety had his moments last season, but ended the campaign on a down note — getting burned by Baylor’s tailbacks and receivers in a 49-26 Holiday Bowl loss.

This spring, head coach Jim Mora said Goforth has a much greater command of the defense, praising his assertiveness in making calls.

“He’s playing with a lot more confidence,” Mora said. “I really believe that experience, even though it wasn’t always positive last year — he struggled in that Baylor game. But I think he went back and he really learned from it.”

Added Goforth, who said he’s up from 175 pounds to 193: “All offseason, I was just getting bigger, getting stronger, getting faster so I can more physical on the field.”

» Replacing tight end/Y-receiver Joseph Fauria as a red-zone threat won’t be easy. No. 1 receiver Shaq Evans figures to get more looks there, as will sophomore Jordan Payton — who has had a solid if not spectacular camp so far.

Also key will be the performance of Darius Bell, whom Mora called one of last season’s most underrated Bruins. The 5-foot-11, 216-pound senior brings completely different dimensions to the spot once filled by the 6-foot-7 Fauria, who had 12 touchdowns last season, but Mora said it’s simply a matter of working with a more normal-sized target.

“He’s nifty,” he said. “I think his quarterback background gives him a great feel for finding openings in zone. I think he’s really in concert with Brett, knowing where to go and when to be there. It’s just going to be different. The ball’s going to be lower rather than higher.”

Bell had seven catches and a touchdown before fracturing his rib in October.

» Special teams and linebackers coach Jeff Ulbrich has an extra title this season: assistant head coach.

“He’s got a tremendous influence on this team because he’s the only other coach besides myself who talks to the team,” Mora said. “He’s the special teams coordinator. I’ve always thought special teams coordinators were really undervalued in terms of their ability to someday be a head coach.”

To underscore his point, Mora brought up John Harbaugh, who led the Baltimore Ravens to a Super Bowl victory in February. Harbaugh was the Philadelphia Eagles’ special teams coordinator for nine years before landing a head coaching job in 2008. (As most already know, he was also passed over for the UCLA job in favor of Rick Neuheisel.)

» Injury report: Safety Dietrich Riley, who separated his right shoulder in the first week of spring practice, will sit out at least another week or two. An MRI on Tuesday revealed some damage to the labrum that requires rehab. Senior receiver Shaq Evans missed Wednesday’s practice with a flu. Offensive tackle Simon Goines participated in practice, but was still limited with respiratory issues.