ALAMEDA — The Oakland Raiders ended their offseason workouts with a very different look than the group new coach Lane Kiffin had at his first practice in March.

JaMarcus Russell and Josh McCown have become the top quarterbacks, Randy Moss has been shipped out and the offensive line has undergone constant tinkering.

The team’s voluntary minicamp ended Wednesday and the next time the players take the field for practice will be when training camp opens in Napa on July 27.

The biggest developments since Kiffin first took over is at quarterback. The Raiders used the No. 1 overall draft pick on JaMarcus Russell of LSU and have been impressed so far with what they’ve seen from him. Russell has shown off his strong arm and has worked on learning the offense and managing the game.

He has split time evenly the past two weeks with McCown after Andrew Walter, who started eight games last season, went down a knee injury that will sideline him until training camp.

“Coming out that first day I was kind of anxious, a little nervous,” Russell said. “Coach gave me the plays over the phone, almost three hours a day before I came up. Before that I never knew how it would be that first day out. I kind of got the hang of it now.”

Russell said he’s improved both mentally and physically since his tentative first practice May 4 and will spend the next six weeks talking with coaches and studying the playbook.

“He’s getting better and better,” McCown said. “Especially this last week or so. I think he’s starting to reach a comfort level with what he’s doing. ... He’s made drastic improvements the last week or so.”

Much of the focus in the offseason moves and in the practices has been on improving an offense that scored 12 touchdowns last season. Kiffin has brought in a new offensive coaching staff and overhauled much of the offense through trades, free agency and the draft.

The offensive line allowed a league-worst 72 sacks and opened few holes in the running game last year. Offensive line coach Tom Cable has brought his cut-blocking schemes from Atlanta, forcing players to learn new techniques.

“Everything is real clear,” lineman Robert Gallery said. “Go out and do things the way we do it well in a friendly system that is going to help us be the best we can be.”

The offseason practices have also given Kiffin and Cable a chance to see players at different positions. Gallery has been getting most of his reps of late at left guard and right tackle after starting at left tackle last season. Barry Sims has been back at left tackle most of the spring after starting at guard last season. Jeremy Newberry, Cooper Carlisle and Paul McQuistan have also been moving around.

“Everybody is excited this year,” center Jake Grove said. “I think everybody is doing the right things, saying the right things. We just have to go out there and make this system work for us.”