Pro Bowl defensive tackle Haloti Ngata returned to practice after missing the past few days to attend to a family issue. He wasn't at practice Sunday and Monday, excused for personal reasons.
Starting defensive end Arthur Jones missed practice for the third day in a row as he deals with a personal medical issue, according to Harbaugh.
Jones was at team headquarters Tuesday, but has been sidelined since the Ravens' 34-27 loss to the Carolina Panthers on Thursday night.
"Art had an issue, it's not football-related," Harbaugh said. "I'm going to leave it to Art to explain what it was. It's more of a personal health thing that's not serious. We just held him back this week."
Thompson on the mend
Wide receiver Deonte Thompson remains sidelined with a sprained left foot. Thompson has been making progress recently, according to a league source.
Thompson got hurt against the Atlanta Falcons in the first preseason game. He hasn't been ruled out for a potential return in the season-opener against the Denver Broncos, per the source.
Although Gino Gradkowski is still regarded as the frontrunner to eventually claim the starting center job, no winner has been declared yet as he continues to compete with former Indianapolis Colts starter A.Q. Shipley.
The Ravens could delay an announcement for tactical reasons.
"Yeah, they still haven't said anything about what's going on," Shipley said. "I just do whatever I can do."
Shipley was penalized twice in his lone start against the Atlanta Falcons, but held up solidly in the other two preseason games.
"I made some mistakes obviously in the second game, but I felt real good against Carolina and Tampa Bay," Shipley said. "That's what the preseason is for, to get those mistakes out of the way."
Cut by the Ravens in July, undrafted rookie quarterback Dayne Crist had been waiting for a call ever since.
That call to return for the final week of the preseason followed backup quarterback Tyrod Taylor being evaluated for concussion symptoms after being hit hard in the fourth quarter against Carolina.
Crist is only expected to be on the roster briefly as the Ravens needed reinforcements for the preseason finale against the St. Louis Rams on Thursday night with starter Joe Flacco definitely not playing and third quarterback Caleb Hanie expected to see extensive action and Taylor potentially sidelined.
"It's been a crazy few months," Crist said. "Tyrod is a great guy. It's tough to see a guy get hurt in a game, but you always have to be ready. I'm just happy to be here and have an opportunity.
"I'm looking forward to the rest of this week and Thursday. It's a dream come true, truly. This is what I've wanted to do my entire life. I feel very fortunate and blessed to be in this situation."
Harbaugh said that Taylor, who's been practicing every day, hasn't been ruled out for Thursday as he's passed the physical balance aspect of the NFL concussion testing protocol.
Players are required to pass baseline neurological testing following a concussion before they're allowed to be exposed to contact again.
"We're waiting for the test result on the other part of it," Harbaugh said. "Haven't heard anything negative on that. As soon as he passes the test, he's cleared to play. We don't anticipate that being a problem. If it is, that would be a little surprising."
Besides Thompson, McClain, Jones and Lewis-Moore, tight end Dennis Pitta (hip surgery) and center Ryan Jensen (foot surgery) didn't practice. ... Olympic gold medalist swimmer Michael Phelps and his girlfriend, Golf Channel reporter, Win McMurry, attended practice as well as retired Ravens Pro Bowl kicker Matt Stover.