STATE COLLEGE — With Penn State limited to 65 scholarship players because of NCAA sanctions, coach Bill O’Brien has said keeping key players healthy is a crucial balancing act.

That balancing act was evident Friday during the 25 minutes the coach opened the Nittany Lions’ 14th practice to the media.

Defensive end Deion Barnes, safety Adrian Amos and wide receiver Allen Robinson, all three expected to be key starters, sat out practice. So did offensive tackle Adam Gress and offensive guard Andrew Nelson.

“That’s a balance we talk about every single day. We’ve got a lot of reps in practice. OK, so let’s say you get 50 to 60 reps in practice. One thing that we try to do is get our No. 1 groups quality, good reps,” O’Brien said at the team’s media day.

“We don’t want to give them 50 million reps in a practice, but we try to get them quality, good reps, and then we try to get the younger players a lot of reps, get those guys in there and let them play football. We try to be creative every single day to make sure our team is as healthy as possible for Syracuse.”

Barnes and Amos sat out as a precaution to safeguard against minor ailments becoming major. Robinson is nursing a minor hamstring injury. Gress, O’Brien said Thursday, “got banged up a little, but he’ll be fine.”

With Gress sidelined, the starting offensive line that appeared briefly in a two-point drill was: Garry Gilliam (right tackle), John Urschel (right guard), Ty Howle (center), Miles Dieffenbach (left guard), Donovan Smith (left tackle).

During that 11-on-11 two-point drill, sophomore quarterback Tyler Ferguson zipped a pass to Kyle Carter on an out route for the conversion. Carter, who is coming back from a wrist injury suffered late last season, used his large frame to wall off the defensive back and snatched the ball out of the air.

On the next play, freshman Christian Hackenberg had his pass to the right flat batted down by a defensive end.

Returning kicker Sam Ficken and freshman Chris Gulla both looked impressive.