ALAMEDA – Coach Dennis Allen on Tuesday got his first on-field look at the players that mostly will comprise the 2014 Raiders, and he came away impressed.

With good reason, too. Defensive lineman Antonio Smith and linebacker Kevin Burnett were the only players from the 90-man roster absent, and Smith wasn’t at the workout only because of a recent surgery.

It’s unclear why Burnett opted to miss the workout, though he isn’t required to be here per the collective bargaining agreement.

“I’ve had communication with Kevin this whole time,” Allen said. “This is a voluntary camp. Players can make their own decisions, and they have families and things in their personal lives that they have to make sure they take care of. I’m not concerned about that at all.”

Allen declined to say whether Burnett’s absence has anything to do with the Raiders selecting linebacker Khalil Mack with the No. 5 pick in this year’s NFL draft.

Burnett played weak-side linebacker for the Raiders last season. Mack figures to get most of his time at the strong-side position. However, many of the team’s linebackers are versatile enough to play more than one position.

“My focus is really on the guys that are here,” Allen said, “and we’re working to try to do everything we can to get better as a football team.”