"He seems like he's on a mission," he said.
And in many ways, he is. He's on a mission to prove that he's healthy and capable of starting in center field for the Astros this year. He's also on a mission to put his previous off-the-field missteps behind him, saying he's matured, grown up and eager to do things the right way.
Schafer, acquired by the Astros along with three young pitchers in last year's trade that sent Michael Bourn to the Braves, understands the opportunity he has in Houston. It's a young team that's rebuilding and provides fertile ground for young players like Schafer to show what they can do.
"It's nice to have basically a fresh start, a new organization," he said. "Just to be able to come in here and try to play and them giving me a chance to succeed, it's nice to have this opportunity."
Schafer, 25, is competing for the Astros' starting center field job, and conventional wisdom says it's his for the taking. He's blessed with streak-of-lightning speed, a strong arm, and remains bursting with untapped potential, even three years after he was named the Braves' top prospect.
"He looks really good," Mills said. "He looked strong last year, but he's grown up a little bit as well, and that kind of adds something."
Schafer's promising career has been slowed by injuries -- he had left wrist surgery at the end of the 2009 season -- and trouble away from the field.
He was suspended 50 games in 2008 for violating baseball's performance-enhancing drug use policy -- he was reportedly linked to HGH -- and last winter was arrested at a traffic stop in Florida and charged with possession of marijuana and drug paraphernalia. He apologized publicly upon arriving to camp this year and took responsibility for his actions.
All of it, he says, has made him stronger.
"The injuries are not a fun thing to go through," Schafer said. "I've been through a lot my entire career, and I think it's all been a growing process, and I think finally the time's come to put the tools and the talent to use on the field. Not that I haven't taken the game serious before, because I have, but it's time to realize it's time to put up the numbers I'm supposed to put up."
Schafer was on the disabled list with a finger injury when the Astros acquired him and he appeared in only 30 games in a Houston uniform in 2011, hitting .245 with one homer, six RBIs and seven stolen bases. In 469 career Major League at-bats, he's hitting .228 with four homers, 21 RBIs and 24 steals.
Eager to make a good impression in his first camp with the Astros, Schafer put on 20-25 pounds last offseason and reported at 206 pounds. He worked out rigorously in Orlando with trainer Tom Shaw, who trains NFL players to prepare for the scouting combine, to improve strength and speed. Those who follow him on Twitter were reminded daily of his commitment to his workouts.
"We'd have weightlifting in the morning for a couple of hours and then we'd run, whether running in sand or running with ropes [as tension]," Schafer said. "We did all kinds of running, hills and speed stuff. It varied. It was really good, and I think it really helped."
Schafer said he was timed in the 40-yard dash at 4.38 seconds, which equals the two-run average of Heisman Trophy-winning quarterback Robert Griffin III at this year's NFL combine. The extra weight was about getting stronger, not slower.
"I was just trying to stay flexible at the end [of the workouts] to make sure I wasn't tight and still in baseball shape," he said. "By no means am I trying to become a bodybuilder where I'm not functional [on the field], so I'm at a good weight. It's going to help me."
Led by Schafer and fellow speedster Jason Bourgeois, the Astros have speed to burn and options in center field. Mills said last week that the athletic Brian Bogusevic, who started the majority of games in right field at the end of last year, would be given a look in center field this spring, too.
Schafer isn't focusing on the competition or anything else at this point other than getting himself ready for what he hopes is his long-awaited breakout season.
"As long as I take care of myself, I'm confident I'll be able to put up the kinds of numbers I need to put up this year to be successful," he said. "I think talent-wise, everything has always been there. I don't think anybody's ever questioned my tools or talent. It's taken a little time for me to mature and grow up, and be able to go about the game the right way. I think with everything that's happened, it's made me mature. I'm ready for this now."