SAN DIEGO -- Fernando Tatis Jr. took another important step toward his return from a partially dislocated left shoulder on Monday -- perhaps his busiest day since he sustained the injury nine days ago.

The Padres' star shortstop (or is he?) took about 50 swings on the field during batting practice, a heavy workload in his first on-field BP since the injury. Tatis hit his usual array of line drives and added a few prodigious homers, including one over the second deck of seats in left field.

Then, Tatis took to the outfield, where he shagged fly balls in center and eventually moved to right field for one-on-one work with outfield coach Wayne Kirby. It seems increasingly possible -- perhaps likely even -- that when Tatis returns, it will be as an outfielder. Though the club maintains that no decision has yet been made on that front.

Internally, the Padres feel as though a move to the outfield might be the best way to preserve Tatis for the stretch run. He has suffered a series of four or five shoulder injuries already this season. The latest dislocation was the worst of the bunch, and it landed Tatis on the IL on July 31. Although he's eligible to return on Tuesday, he is not ready just yet.

At the minimum, Tatis is looking at a few more days of rehab -- during which he'll continue to get pregame reps in the outfield. The early returns are positive.

"He's seeing the ball well off the bat," Kirby said. "His instincts are impeccable. He shouldn't have any problem. His speed will make up for the adjustment."

Don't read into that as a definitive statement, Kirby added. Tatis has said he'd be open to the move; Kirby has been tasked with providing him instruction. But the decision will ultimately be made by general manager A.J. Preller and manager Jayce Tingler -- and it won’t be formally made until Tatis' return date approaches.

"That's up to A.J. and company," Kirby said. "That ain't up to me. My job is to get him as comfortable as possible out there. If the decision comes that he's playing in the outfield, he'll be ready for that."

Tatis' pregame reps have come exclusively in center and right field. It's unclear where exactly Tatis would play in the outfield, but it seems safe to rule out left field, per Kirby, who quipped that Tatis might have "too much arm for left."

Of course, the first priority is getting Tatis healthy. Each partial dislocation increases the likelihood of another one occurring. Surgery would stabilize Tatis' shoulder and help prevent future injuries -- but it would also end his season.

Needless to say, the Padres would prefer to avoid surgery, at least until the offseason. Even with his three stints on the injured list this season, Tatis leads the National League with 31 homers and 23 steals, while hitting .292/.373/.651. He's the front-runner for the NL MVP Award.

Locked in a playoff race, the Padres need his bat back in their lineup, and they think a position switch might be the best way to ensure they do.

"It's kind of hard to tell a kid that you're not supposed to dive, and you're not supposed to do this, because instincts take over," Kirby said. "Playing shortstop, every once in a while, the ball becomes out of your reach, and you have to dive to make the play. In the outfield, it all depends on your jumps. You get a good jump, you don't have to dive."

Starting Stammen
What a world: Tatis might be headed to the outfield. And longtime reliever Craig Stammen might be headed to the starting rotation.

The veteran right-hander appears set to fill the void at the back end of San Diego's rotation -- and not merely as the first in a line of one- or two-inning bullpen arms. Stammen will start Tuesday’s game against the Marlins, with the plan to build him toward a regular starter’s workload.

"He's been throwing the ball very well all year," said Tingler. "[We have] the mindset to be able to build Craig up a little bit as well. What does tomorrow look like? We're not going to cap anything. Is it 2-3 innings? If he continues to feel good, the next one, can he go 4-5?"

It's a creative solution to the Padres' thin rotation problem. They didn't add a starter at the Trade Deadline, then right-hander Chris Paddack landed on the injured list with a strained oblique. Ryan Weathers has struggled. Beyond Yu Darvish, Blake Snell and Joe Musgrove, there are serious question marks.

Stammen, meanwhile, owns a 2.71 ERA this season in a relief role. But his absence wouldn't be felt too hard in a bullpen that is one of the deepest in baseball.

Then again, Stammen hasn't served as a traditional starting pitcher since 2010 in Washington. He's not even ready to call himself a starter just yet. The Padres are merely asking him for outs, he says. He’s ready to get them, no matter when, no matter how many.

"My main principles are going to be the same,” Stammen said. “I think I've learned to become a better pitcher as I've moved to the bullpen and become older, so I'm going to use some of that experience and try not to pitch like I did when I was a rookie. Just get after 'em."