* Quarterback battle: O'Brien reiterated that the best player is going to play, saying he does not want to redshirt highly touted recruit Christian Hackenberg if he is healthy.
He said the two quarterbacks in camp who will compete for the starting role, rising sophomore Steven Bench and rising redshirt sophomore Tyler Ferguson, "sit in the front row" during meetings and want to be coached.
"It's going to depend on how well they make decisions and how well they throw the ball," O'Brien said.
* Linebackers: With rising redshirt sophomore Ben Kline sidelined from spring practice with a shoulder injury, O'Brien said he looks forward to seeing how the trio of rising senior Glenn Carson, rising redshirt junior Mike Hull, and Philadelphia native rising redshirt freshman Nyeem Wartman play together.
"All three of those guys have really had excellent offseasons," the coach said.
But the main point O'Brien stressed about the position was a lack of depth. The Lions are losing two stars in Michael Mauti and Gerald Hodges, so O'Brien noted that it will be imperative that his linebackers not get too many reps in early practices.
* Running back: Last season, then-sophomore Bill Belton was the No. 1 guy in the backfield in Week 1. But after he missed a few turns with an ankle injury, the position became a revolving door until sophomore Zach Zwinak solidified his spot as the starter, finishing the year with 1,000 rushing yards on 203 carries.
Zwinak and Belton will again be in the mix, as will rising redshirt freshman Akeel Lynch, who came to Penn State as a three-star recruit.
"I'd love to be able to tell you exactly what I want to do with the running backs, but that'd be awful stupid of me to do that," O'Brien said. But O'Brien did give praise to them, saying he thinks they all bring different skills to the table: Zwinak has the bruising size, Belton the speed, and Lynch is somewhere in between.
* John Butler as defensive coordinator: Butler, a graduate of La Salle High, was promoted from special teams/secondary coach this offseason after the departure of Ted Roof.
The foundation of the defense and the terminology will remain mostly the same, O'Brien said, and there is confidence in Butler.
"John, he's an excellent football coach," he said. "A lot of you guys have been to practice and watched him coach; he's very detailed, he's intense, he's a quick thinker, he's done it before."
* Injuries: Besides Kline, rising redshirt sophomore tight end Kyle Carter, who broke out to the tune of 36 catches for 453 yards last season, won't be participating in full-contact drills because of a wrist injury. Senior safety Steven-Obeng Agyapong is in the same boat with a "shoulder deal."
Former five-star recruit and rising freshman tight end Adam Breneman (torn ACL) will be monitored in spring practice early.