BETHLEHEM, Pa. -- Running back LeSean McCoy missed practice with a quadriceps contusion, the Eagles said. The severity of the injury is unknown at this time but it does not appear to be serious.

A contusion, in layman's terms, is a bruise, and McCoy probably received one of those dings that many NFL players get nowadays because they often don't wear thigh pads.

McCoy said the injury occurred during Sunday morning's practice when, he thinks, Ernie Sims hit him. He continued to play and even took part in the afternoon session.

"It's just one of those things that happened," McCoy said Monday afternoon. "It hurt to run, but I'll be OK."

With McCoy out and Mike Bell nursing a calf strain, Eldra Buckley moved up to the first team and Martell Mallett played with the backups. Mallett even got some repetitions with the starters during a "live" red zone period in which the first team offense took on the first team defense.

It was the first time this camp that the starters faced off in a full-contact period. The result was a draw. The offense scored twice with Kevin Kolb passing to Mallett underneath and the tailback running into the end zone both times. The last score came on a shovel pass. Defensive end Juqua Parker read the play, but Mallett carried Parker and just crossed the line. Or did he? It was close and the defense protested. Eagles coach Andy Reid called it a touchdown. We'll check the tape.

Mallett hyperextended his left knee when the second team units butted heads. He went to the trainer's tent to get a look-see, but he was able to walk off the field. J.J. Arrington made an appearance at practice after missing the last week or so with a foot contusion. Chad Hall once again took reps with the running back during individual drills and played some halfback during team drills.

-- Speaking of contact, Ernie Sims still can't seem to decipher the meaning of the word. He thumped tight end Brent Celek during a non-contact drill, his fourth or fifth act of over-aggressiveness this camp.

"That all started the play before," Sims said. "Leonard Weaver came through the hole and he actually got across the goal line. Sean McDermott wasn't happy about it, so it put a little fire in us. The next play I took advantage of the opportunity and I took a shot on Celek. It's something that I got to probably tone down."

Reid gave Sims a tongue-lashing afterward as Celek lay on the ground.

"Coach Reid ... pretty much said to take care of your teammates," Sims said.

The linebacker said that he hadn't yet spoken to Celek.

"We're good," Sims said. "We're out here playing football. We're out here working hard. At the end of the day both of us understand that we got our goals."

Celek later said he had the wind knocked out of him.

"That's part of football. It's not a big deal," Celek said. "That stuff is going to happen in a game."

-- The Eagles finally signed a safety, inking Penn State alum and West Deptford, N.J. native Anthony Scirrotto after working him out earlier in the day. Safety Antoine Harris was thus placed on injured reserve. The Eagles had worked out three other safeties over the last two days but decided on the 6-foot, 202-pound Scirrotto.

Scirrotto spent time on the Giants practice squad in 2009, after initially signing with the Panthers as a rookie free agent.

-- Center Nick Cole (knee) was also absent from practice after returning briefly for Sunday's afternoon session. With Cole out, Mike McGlynn was back with the first team at center. Center Jamaal Jackson and guard Todd Herremans (foot) were in pads for the second day in a row.

Jackson, who is coming back from knee surgery, even did some sled-pushing. He left before the hitting started. Herremans did slightly more than he did Sunday, jumping in for a few plays during the full contact portion of practice.

-- Safety Quintin Demps (knee) was participating in the early portion of practice. He injured his knee in Friday's game against the Jaguars.

-- Also, the Eagles brought back defensive end Eric Moncor, who was released a few weeks ago. This is the third time this camp that the Eagles have released a player only to bring him back. Wide receiver Jared Perry and Mallett were let go and brought back within days, although Mallett's return had something to do with the waiver not going through the league office.