ST. PETERSBURG, Fla. — Start with the “legendary’’ bat speed. The Yankees acquired a can’t-miss outfielder in right-handed-hitting Clint Frazier, the centerpiece of Sunday’s Andrew Miller trade with the Indians. That’s the word from multiple scouts and even Yankees catcher Brian McCann — like Frazier, a Georgia native.

“I was rehabbing my shoulder and he was getting ready for his senior year,’’ McCann told The Post after the Yankees’ 5-3 loss to the Rays at the Trop on Sunday. “He’s super talented. I know in high school he did a lot of things. He has speed, power. He’s impressive.’’

Frazier, who is listed at 6-foot-1, 190 pounds, could be a center fielder — some scouts say a poor man’s Mike Trout — or could wind up at either corner-outfield position.

“It’s not fair to compare him to Trout but he definitely has power, a middle-of-the-order threat who is going to play well in that park for sure,’’ said one scout.

“Everyone who goes in to watch him always comes out and says, this is one of the quickest bat speeds I have ever seen,’’ said another talent evaluator. “Combine that with his plus raw power and his plus raw speed. There’s home runs and there are stolen bases, but there’s always been swing and miss. This is the kid with the upside — the raw power, the tools, the athleticism and the risk.

“That elite bat speed at times has gotten him in trouble because he is so quick that really good breaking balls, really good spin, can cause a problem. He’s really tightly wound, he’s in fantastic shape. There’s many of those medium body comparisons. The work ethic, the makeup is good. It’s a good get.’’

Said Yankees general manager Brian Cashman: “Frazier has an electric bat. His bat speed is already legendary. He can hit with power and play all three outfield positions. He’s a high-energy guy who shows up for the national anthem in a dirty uniform. He’s a super-competitive guy and I can say the same thing about Justus Sheffield. He is a competitor on that mound. Those two are exciting additions.’’

Frazier, 21, the fifth-overall pick of the 2013 draft, will go to Triple-A Scranton/Wilkes-Barre, while Sheffield, a lefty starter, will go to Single-A Tampa.

“Physically, he is fully developed,’’ noted another scout, saying Frazier could be a 20-homer, 20-steal player who could hit around .280. The scout went on to say that Frazier has an angled swing, similar to Josh Donaldson. “He doesn’t need a ton more time.’’

Scouts like Sheffield’s arm, saying the 5-foot-10, 196-pound lefty’s velocity continues to build. “He’s in the 92-95 [mph] range now with a plus changeup,” one scout said. “His ceiling is probably a No. 3 starter.’’

Back home in Tullahoma, Tenn., in January 2015, Sheffield was arrested for aggravated burglary and violation of the drinking age.

“He had that issue,’’ one scout noted, “and that may have scared some teams away, but he’s got a really strong support system now within his family and that has really helped him.’’

Sheffield was the 31st player taken in the 2014 draft, signing for $1.6 million, and has a brother pitching in the Dodgers organization.

“He’s an undersized kid, a medium-body kid,’’ said one scout. “It’s not a lot of length or wingspan but there is just plus stuff. The breaking ball is considered plus, there’s a good changeup in there. Don’t be deceived by the limited size. This kid’s got plus stuff and you’ll be happy with him.’’

Righty Ben Heller, one of the two other prospects acquired, figures to be a strong bullpen piece who owns a 97-mph fastball. While scouts say J.P. Feyereisen figures to be a middle reliever, his velocity has improved too so he could move up quickly.