GREEN BAY -- Mike McCarthy's evaluation of the first practice was, well, it was the first practice.

Some "clean" looks in the passing game were offset by a couple of fumbles by rookie running backs on offense. Ball security is always a top priority, so that will be the main issue to get cleaned up in the early stages of training camp. Though McCarthy also gave the defense credit for getting the ball out on those plays.

"We had ball on ground too much, a few players on the ground too much," McCarthy said before Friday morning's second workout. "The drill work was really good. We had some clean execution out there, a couple great combination blocks, some great examples of guys getting off blocks, DBs breaking on the ball, a lot of good video. But it was Day 1. We're off to a solid start."

CB Herb Waters dropped out of Thursday's opening practice and McCarthy said he is sidelined for now with a shoulder injury, which affected him in the spring as well. Rookie TE Aaron Peck also missed the opening practice, along with the two players on PUP (LB Vince Biegel, CB Demetri Goodson).

Other notes from McCarthy:

--WRs Randall Cobb and Trevor Davis both could be factors in the return game this season. Cobb has plenty of experience at it, and Davis has built his body physically coming off his rookie season.

--Pads will go on for the first time Saturday, which will begin a more true evaluation of the Packers' rookie running backs, particularly in pass protection. "It's definitely a skill. You really can't practice it or simulate it until you put those pads on," McCarthy said.

Packers.com will have more following practice and locker room interviews.