ST. PETERSBURG -- Jake Fraley has earned his first Major League callup, one of the most prominent promotions in the Mariners’ self-professed “step-back season.”

Fraley, the Mariners’ No. 8 prospect according to MLB Pipeline, will join the big league club in St. Petersburg, where its outfield-depleted roster is in the midst of a three-game series against the Rays. Fraley was scratched from Triple-A Tacoma’s lineup on Monday, and he was officially called up Tuesday when Seattle placed Domingo Santana on the 10-day injured list with right elbow inflammation.

Fraley arrived at Tropicana Field one hour prior to first pitch Tuesday.

The 24-year-old has progressed as rapidly as any position player in Seattle’s farm system this season, and he is a big part of its plans when it hopes to return to a more competitive footing. In that vein, the front office will get its first look at the new wave of prospects that it injected into a once-depleted and now-blossoming farm system, listed No. 11 in MLB Pipeline’s latest rankings.

Fraley will also fill an immediate outfield need at the big league level, where infielders Tim Lopes, Austin Nola and Dylan Moore have been splitting time in left field due to injuries to Mitch Haniger, Braden Bishop and Santana. Fraley took over the center-field job from No. 10 prospect Kyle Lewis at Double-A Arkansas this season, and he projects as a plus defender there. Fraley, Lewis and No. 1 prospect Jarred Kelenic -- the key return in the Edwin Diaz/Robinson Cano trade on Dec. 3 -- could comprise the club’s outfield long term.

“I’m anxious to see how it plays out,” Servais said. “Give him an opportunity, and you’ve got to let them get comfortable. I think the biggest thing when you bring a young player up is you kind of let them show you who they are. Before you start making a ton of changes or anything like that, just get them acclimated to the program here with us.”

After wowing in Spring Training, Fraley propelled from Arkansas to Tacoma and was slashing a combined .298/.365/.545, with a career-high 19 homers and 80 RBIs, perhaps even exceeding management’s expectations. The club touts his disciplined approach as the root for his significant offensive progression this season, with pitch selection and his increased power.

“He's had a really big first half in Double-A, and coming here, he really didn't slow down a whole lot,” Tacoma manager Daren Brown said. “He tries to work to get good pitches to hit and then it's about not missing them. He's done a really good job of that. Obviously, a level change, there's going to be more offspeed pitches than what he saw in Double-A, and he's handled it all pretty well. He’s made adjustments when he needed to. He really hasn't gotten into any struggle or slump at all. He's been pretty solid and consistent.”

Fraley is one of many acolytes in the launch-angle era that created more lift in a once-flat swing, which, coupled with his increased strength, has led to more power. He is also healthy after battling significant injuries from 2017-18. Fraley missed one week earlier this month with a quad injury, but has played in 99 games this season, 33 more than his previous career high in 2018.

Fraley will be returning home in a way. He was a Comp Round B Draft pick (between second and third rounds) by Tampa Bay in 2016 and was acquired by Seattle as the key return in the Mike Zunino trade last Nov. 8, with Mallex Smith.

Santana exited early on July 23 against the Rangers with right elbow soreness and hasn’t played in the outfield since. The 27-year-old has six hits in 49 at-bats as a designated hitter since, with a double, two home runs, four RBIs and two stolen bases.

Servais said once Santana admitted Friday he was playing through some discomfort at the plate and when stretching his throwing program to 60 feet, it made sense to give Santana a breather.

“We thought at that point let’s let this calm down, give it 10 days, a couple of weeks, whatever it takes,” Servais said. “I really want him to finish the season strong. He had such a good first half.”