FORT MYERS, Fla. -- Change is coming for Chris Archer.

Archer starred with the Rays last season, notching the American League's highest average fastball velocity for a starting pitcher and finishing third in the AL Rookie of the Year Award balloting. But now, with an encore in sight, Archer is working on a changeup to round out his repertoire.

According to FanGraphs, nobody -- not Justin Verlander, Yu Darvish or anyone else -- averaged more than Archer's 95 mph on his fastball last season, and the Rays are comfortable letting that pitch ride. But if Archer can change speeds and keep hitters off-balance, he can be even better.

Archer has been working on refining his four-seam circle changeup grip, and he said he doesn't mind if there's only a six or seven mph difference between his changeup and his fastball. Archer threw the pitch three or four times in his spring debut Tuesday, and he was thrilled with the way it worked.

"I think it's just an added weapon to my arsenal," said Archer, who also throws an effective slider. "It will be something that they'll have to respect and it will make my other pitches better."

Archer was impressive as a rookie last season, but his splits showed a disturbing trend. The right-hander held same-side hitters to a .176 batting average and a .218 slugging percentage in 193 at-bats, but left-handed hitters reached him for a .261 average and a .471 slugging mark.

And that's where the changeup comes in. If Archer can show that he can throw the pitch effectively, he can keep left-handed hitters from sitting on his fastball. Manager Joe Maddon also wants Archer to improve on his control, and if he does, the 25-year-old can really improve his game.

"Fastball command and something that really bothers left-handed hitters," he said of Archer's keys for success. "There's different things we're working on in regards to his defense too, but for him to take it to the next level, he needs a little bit better fastball command and something that bothers a lefty."

Archer said that each of the changeups he threw was down in the strike zone on Tuesday, and he said that the pitch was only called for a ball once. Even that pitch was exactly where he wanted it, though, and Archer is enjoying the experiment of using the changeup early and late in the count.

"Right now, it doesn't matter," Archer said of the timing. "It's weird, but the Rays would rather me fail trying than to not try at all. Regardless of the count, they want me to go out there and practice it."

There wasn't a huge amount of time for Archer to work on Tuesday, but he retired six of the seven batters he faced. The former fifth-round draftee said it helped him to be facing the defending World Series champion Red Sox, and he took special satisfaction from one particular at-bat.

Archer got to face off against cleanup man David Ortiz on Tuesday, and the righty struck out the nine-time All-Star on a back-door slider. For Archer, that at-bat meant everything. It's one thing to imagine how you'll face off against an elite hitter, but it's another thing to actually do it in your spring debut.

"I was happy," said Archer. "I'm a big person on visualization. I visualized that pitch. I do it out in the bullpen, but nothing is like executing it in a game to one of the best hitters of all-time."

Archer, who was acquired from the Cubs in 2011 as part of a trade for Matt Garza, was rarely challenged on Tuesday. He got a ground ball, a liner and the Ortiz strikeout in the first inning, and after a leadoff single in the second, Archer managed to coax a double play and a line drive to end the inning.

When it was over, veteran catcher Jose Molina raved about Archer's day of work.

"For his first outing, he was really good," said Molina. "We always talk about being consistent, and the more consistent he is, he's going to be even better. We've been talking a lot about that, about every pitch being consistent. For it being his first outing, he got a really good couple innings there."

Archer, for all his skill, is succeeding with the Rays because of his preparation and perspective. The youngster was asked Tuesday if his mindset has changed since experiencing success at the Major League level, and his response spoke volumes about the kind of player he's becoming.

"I've been thinking about that and I knew somebody was going to ask me," said Archer of how much his comfort level has increased after having success in the Majors. "Honestly, it's the same comfort level I've always had, because ultimately, it's not just to be successful, it's to maximize my potential. Right now, I don't even think my potential is in sight. I have a lot more work to do to get there."