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Luis Severino was two outs into the seventh inning and 106 pitches into his day's work when Jose Peraza stepped to the plate on a recent Wednesday afternoon at Yankee Stadium. Two unearned runs had already scored in the inning, but New York Yankees manager Joe Girardi let his 23-year-old ace continue.

A year after plenty of people were calling for Severino to be left full-time in the bullpen, Girardi was willing to let him be his own setup man. And why not?

First pitch to Peraza: A 99.8 mph fastball, taken for strike one.

Second pitch: A 99.9 mph fastball, fouled off for strike two.

Then three straight attempts to make Peraza chase—a pair of sliders (90.5 and 90 mph) and a changeup (90.3 mph).

Finally, another fastball, at an even 100 mph, and all Peraza could do was bounce it high in the air and back to Severino, who barehanded it and threw to first.

So yeah, Severino is a starter, and not just because he has a 3.18 ERA pitching exclusively in that role in 2017. Severino is a starter, with a chance to be great, because the great starters are the ones who can do what he did that day against Peraza and the Cincinnati Reds. Even in this era where teams are hesitant to let starting pitchers go through a batting order a third time, the great ones maintain their stuff to the point where they can do exactly that.

The great ones don't want to come out of games. Even after 112 pitches, even after that sequence to finish the seventh inning, Severino didn't want out of that one.

"I was feeling good," he told B/R. "I could have gone one more."

In a Yankees season where so much of the early focus was on Aaron Judge and so much of the recent focus has been on newly acquired Sonny Gray, the biggest development of all may well be the emergence of Severino as the homegrown ace, for a franchise that hasn't developed a starting pitcher with staying power since Andy Pettitte arrived in the major leagues in 1995.

His ERA ranks fourth in the American League. His 10.46 strikeouts per nine innings rank fourth. According to MLB.com's Statcast, his 97.3 mph average fastball velocity is highest among full-time major league starters, and a 101.2 mph fastball he threw July 20 in Seattle is the fastest single pitch thrown by a major league starter this season.

Severino, 46 starts into his career, is already in position to shoot past the other touted starters who have come through the Yankees system since Pettitte. Phil Hughes won 18 games one year and made an All-Star team, but he was hardly a classic ace. And Chien-Ming Wang had two 19-win seasons, but he was never an All-Star.

Severino was an All-Star this year, in his first full season as a big league starter, six years after the Yankees signed him out of his native Dominican Republic for just $225,000.

It wasn't all that much money in a year when Baseball America said the Texas Rangers gave 16-year-old Nomar Mazara $4.95 million, and three pitchers who signed on the international market got bonuses of $1 million or more.

"It was the age," Severino said. "I was almost 18."

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The best prospects from the Dominican Republic often sign when they're 16. Severino, two months shy of his 18th birthday, was considered a little too old to be worth the big bucks.

"I didn't throw hard when I was 16, maybe 84-86," he said. "I started throwing hard when I was 17. I had a nasty slider, too, better than I have now. The Yankees said that's why they wanted me."

They almost didn't get him. Severino said he had already signed some initial paperwork with the Colorado Rockies when a Yankees scout came to him with an identical offer and got him to switch.

"I was a Yankee fan all my life," he explained. "When I was growing up, I was a hitter, and I loved A-Rod [Alex Rodriguez] and [Robinson] Cano."

Too bad for the Rockies he didn't love Todd Helton, Troy Tulowitzki and Carlos Gonzalez.

It didn't take the Yankees long to realize they had something special.

Severino didn't throw as hard then as he does now, but he had a 1.68 ERA in 14 starts in the Dominican Summer League.

"He had a very quick arm," Mark Newman, then the team's vice president of baseball operations, said in a 2015 interview with Brendan Kuty of NJ.com. "He was athletic. He had a feel for the strike zone."

He had more than that. Teammates quickly realized Severino had the right makeup to succeed. He worked hard, and he picked up English quicker than many other kids from the Dominican Republic.

"He's got the mentality of a winner," first baseman Greg Bird said in a Bleacher Report story I wrote about Severino a few weeks after his big league debut in 2015. "You've got to have poise. He's special, talent-wise and his head. He's got a good head."

He needed it last year, when he came into the season with a spot in the Yankees rotation that he couldn't hold onto. Perhaps it was that he had bulked up, perhaps the pressure of expectations got to him, or perhaps it was just normal growing pains for a young pitcher.

Whatever it was, Severino found himself back in Triple-A for June and part of July, and again for a while in August. When he returned to the big leagues, it was mostly as a reliever, and he was impressive in that role, with a 0.39 ERA in 11 appearances.

All along, though, Severino maintained he was a starting pitcher.

"I think I was kind of wasting my time in the bullpen," he says now. "I knew I could give more than that. I knew I could give six or seven innings."

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He also knew he would need to show it this season. Severino dropped some of the weight he had added, worked hard on getting confidence in his changeup and sought help from Pedro Martinez, who may not have been eager to help the Yankees but was more than willing to aid a fellow Dominican pitcher.

"He helped me a lot, mostly on my mechanics," Severino says, demonstrating a change-up Martinez suggested in which he keeps his hands closer to his body during his delivery. "It really helped my fastball command."

Severino isn't using the change-up significantly more often than he did when he was starting last season, but he is using it more effectively. According to BrooksBaseball.net, opponents are hitting just .159 when they put Severino's changeup in play, compared to .242 in 2016.

Meanwhile, his fastball keeps getting better. He's throwing harder than ever this season, and regularly holding his velocity deep into games. Severino said he's not sure why, but he feels stronger four or five innings into a start than he does in the first inning.

It shows. There have only been four times this season a starting pitcher has thrown a 100 mph fastball after the sixth inning, according to Statcast. One was by Carlos Martinez of the St. Louis Cardinals. The other three? Severino.

Those aren't isolated incidents, either. Statcast shows Severino has thrown 52 pitches at 98 mph or above from the seventh inning on. No other big league starter has thrown more than 17 (also Martinez). All the other starters combined, besides Severino and Martinez, have thrown just 44.

Severino's teammate CC Sabathia said Justin Verlander and the young Bartolo Colon were the only other pitchers he's seen who maintained 100 mph stuff as deep into a game as Severino.

"I think the guys who really put up big numbers are able to [maintain their stuff]," Girardi said.

Because Severino can do it, Girardi has allowed him to start the seventh inning 16 times in 24 starts, quite a statement on a team with a deep bullpen. Far from crumbling after he sees hitters twice in the same game, Severino's numbers are actually better the third time through, according to Baseball-Reference.com.

Opponents have a batting average of .200 against Severino the third time they see him, as opposed to .224 and .232 the first two times.

He's a starting pitcher for sure, a very good starting pitcher. And the numbers suggest he could become a great one.

Danny Knobler covers Major League Baseball as a national columnist for Bleacher Report.

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