Mario Cristobal’s national signing day press conference was already well underway when Oregon’s compliance office gave the coach permission to talk about his prize prospect.

Penei Sewell was worth the wait.

The Ducks beat Alabama and USC on Wednesday for the 6-foot-5, 350-pound offensive lineman, who added some weighty four-star power to the 23-man recruiting class.

“It’s a great example of the types of battles that Oregon is capable of winning,” Cristobal said. “He’s an ultimate difference maker. … Penei kind of caused an explosion in the room when it was official.”

Despite the ill-timed loss of Willie Taggart and the loss in the Las Vegas Bowl late in the recruiting cycle, Cristobal and his staff were able to secure a class ranked 15th nationally by Rivals and 16th by 247Sports.

Oregon added eight prospects on Wednesday after landing 15 players during the early signing period in December.

The program also announced that DJ Johnson — one of the highest-ranked defensive line prospects in 2017 — has officially transferred to Oregon from Miami.

“I do think it’s important to note that if DJ was actually counted as part of this class, OK, there are very few guys like him, where does this class stand?” Cristobal said. “This is a really, really big deal for us. … Those guys are hard to find.”

Johnson probably will have to redshirt in 2018, per the NCAA transfer rules, but several recruits will have an opportunity to contribute immediately.

The Ducks added four pass-catchers from California — wide receivers Isaah Crocker, Jalen Hall and J.J. Tucker, and tight end Spencer Hall — who will all compete for playing time as true freshmen.

Several high-profile receivers decommitted after Taggart departed for Florida State, including two players who also took their talents to Tallahassee (Warren Thompson and Tre’Shaun Harrison).

“We probably fell a little bit short at the wide receiver position in terms of numbers. We wanted another one or two,” Cristobal said. “We were able to get three and had the tight end Spencer Webb, who played a lot of wide receiver all year long.

“So you’ve got four guys that can make a difference in the passing game. That was of utmost importance.”

Cristobal plans to continue coaching the offensive line and welcomed Justin Johnson, who he dubbed the “human eclipse,” to the unit when the 6-foot-7, 342-pound prospect from Philadelphia sent his paperwork in at 4 a.m. Wednesday.

In addition to Sewell and Johnson, Oregon signed offensive linemen Dawson Jaramillo (6-5, 295), Steven Jones (6-6, 340) and Christopher Randazzo (6-7, 330) in December.

“The amount of size and power that we added to the offensive line was critical,” Cristobal said. “I think we have a great offensive line right now. These guys will complement it right away and will push us to get better and for playing time and to be contributors.”

Linebacker Andrew Johnson of Tifton, Ga., signed on Wednesday, joining a position group that added four-star recruits MJ Cunningham and Adrian Jackson in December.

“Huge news! The surprise!” defensive coordinator Jim Leavitt tweeted after Johnson’s letter of intent arrived. “Went into Georgia and got a GREAT ONE!!!”

Oregon’s class includes players from 11 different states with six defensive backs, four offensive linemen, three linebackers, three wide receivers, two defensive linemen, two running backs, a quarterback, a tight end and a long snapper.

“When you announce a long snapper, no one gets all fired up. I do,” Cristobal said of signing Karsten Battles to replace the graduated Tanner Carew, who is currently preparing for the NFL Scouting Combine. “It might be the first time I ever saw a highlight film that actually just showed the long snapper whipping five, six snaps back there. I thought it was a riveting experience for everyone that was there.”

Quarterback Tyler Shough is among the members of the 2018 class already enrolled at UO early to participate in the strength and conditioning program and spring practice.

Cristobal believes the other true freshmen who will arrive in the summer are all worth the wait.

“Whatever it ends up being ranked … I know it’s one of the top classes in the country,” Cristobal said. “I know when you start looking position by position, for the most part we got the top guys in the areas that we targeted. And that is the most important part.”

Follow Ryan Thorburn on Twitter @rgduckfootball . Email ryan.thorburn@registerguard.com .