John Greco couldn't have sounded less surprised.

As the Browns opened OTAs on Tuesday, there was Alex Mack in the middle of everything. The Pro Bowl center, who was last seen in mid-October riding out of FirstEnergy Stadium on a motorized cart, has been on the field with his teammates for weeks, but Tuesday served as the first time media members got a glimpse of him back in his No. 55 jersey and working with the first-team offensive line through a variety of walk-through drills.

A little more than seven months since he severely injured his leg, Mack was "ready to go," Browns coach Mike Pettine said.

"He's kind of shattered expectations," Greco said. "As you would expect."

And as you'd expect, the Browns are exercising every possible precaution with Mack as the intensity of their offseason workout program intensifies.

Though Mack was active during the early portion of practice, he was a bystander when the team went through 11-on-11 drills. Greco, who was Cleveland's regular starter at right guard last season, filled in for Mack while rookie Cameron Erving lined up at right guard.

Still, there's plenty for Mack to accomplish over the next three weeks.

"That's just something where we just want to probably be a lot more conservative with it," Pettine said. "He'll be able to do anything where there's no risk of a collision or getting tripped up."

Pettine said Mack would be "full go" at training camp in late July.

"He approached it as you would have expected him to," Pettine said. "We talk to our guys about being relentless in everything they do – not just on the field, but carry that over in the classroom, the weight room, anybody that has an injury approach their rehab that way, and that's what he's done. It's to no one's surprise that he's back, and he'll be full go for training camp."

With reporters surrounding him after practice, Mack had his feet firmly entrenched in the present. Any talk about the rehab work that's brought him back to this point or his future with the Browns beyond 2015 was swiftly dismissed.

Though he looks back on 2014 with a sense of frustration, Mack isn't impatient as he eyes the upcoming season. He understands the mindset behind the methodical pace of his return to full action.

"I want to be out there healthy. I'm not used to being injured, I'm not used to being on the sidelines," Mack said. "I wanted to be in there, I wanted to be healthy, I wanted to be with my friends, my teammates, so that was very tough.

"There's no game coming up this week so just to be smart about it and let things develop is a good move."

Without Mack in the center of their offensive line, the Browns were able to win some games, but the running game never quite clicked like it did with him in the lineup. In the three games directly after Mack's injury, Cleveland ran for 69, 39 and 56 yards, respectively, against the Jaguars, Raiders and Buccaneers.

Mack is reluctant to pin the Browns' running game struggles on his exit from the lineup, instead pointing toward Cleveland's opponents gearing up their defensive schemes to stop the Browns' ground game. His teammates have been more willing to express just how important Mack was to the 2014 offense.

Even on a day in which Mack wasn't a full participant, there was noticeable excitement from those closest to him.

"He's a pro. He's going to come back stronger and better than ever, I'm sure," Greco said. "I know we're happy he's back in the room and around us."