A few minutes after the Mitchell & Ness Nostalgia Co. opened its doors on a hot summer morning in Philadelphia's Center City district, two baseball greats walked in. In town for a three-game series against the Phillies, longtime Yankees star Carsten Sabathia and Hall of Famer Reggie Jackson wound their way inside the clothing store. A few employees and a young customer holding a Minnesota Timberwolves throwback cap noticed the pair as soon as they walked through the glass doors.
"I can't believe that Reggie Jackson is standing there," a clerk whispered to her colleague as the Yankees' special advisor walked over to a rack of baseball jerseys. "I don't get starstruck that often, but it's not every day that you see Reggie Jackson."
As Jackson and Sabathia conversed about the legendary players whose jerseys hung in the store -- greats such as Cal Ripken Jr., Kirby Puckett, Mike Schmidt and even Mr. October himself -- a fan worked up the nerve to say hello.

"Great game last night," the man said about the Yankees' 4-2 victory over the Phillies on June 25. "I hope we can keep it going tonight."
"Oh, we will," Sabathia responded. "We've got Sevy on the mound, so you have to like our chances. We win when he's out there."
Sabathia's comment was off the cuff, but it was on the mark. It spoke volumes about the respect the seasoned veteran has for Luis Severino, the Yankees' off-the-charts right-hander who came into his own last season.
Severino was slated to face a contending Phillies team later that night in a pitching matchup with Jacob Arrieta, who has been one of the National League's top starters since winning the 2015 National League Cy Young Award with the Cubs.
None of that gave Sabathia -- or Jackson, who quickly turned his head and gave the pitcher a thumbs-up seal of approval -- pause. Their confidence in the Yankees' 24-year-old ace was well founded, especially considering what Severino had already accomplished in 2018.
Following a breakout campaign in 2017 -- when he won 14 regular season games, posted a 2.98 ERA, was selected to the American League All-Star team and finished third in the AL Cy Young Award voting -- Severino has been even better this year.
Through 18 starts, Severino's ERA was a full run lower than where he finished in 2017. Besides the American League-best 1.98 ERA, Severino's 13-2 record gave him the best winning percentage (.867) in baseball among qualified pitchers -- and a second straight All-Star nod.
But those statistics only begin to explain Severino's dominance and, more significantly, how important he has been to the Yankees.
In Severino's first 18 starts, the Yankees went 16-2 -- the most team wins in games started by a single pitcher in baseball. At that time, Severino had allowed three runs or fewer in 15 consecutive starts, a league-leading streak he shared with Mets right-hander Jacob deGrom.
While Severino gave the Yankees a chance to win virtually every time he took the hill, he was a one-man show on several of those occasions. Starting with an Opening Day gem in which he twirled 5 2⁄3 innings of one-hit ball at Toronto, Severino produced six outings of at least that length in which he didn't allow a run.
From the visiting dugout at Citizens Bank Park in downtown Philadelphia a day before he took on the Phillies, Severino explained how he has stepped his game up in 2018.
"I threw a lot more innings last year than I ever had," Severino said. "I knew going into this season that I needed to be better conditioned, so along with my lower body workouts, I did a lot more running. That's been the main thing since the beginning of the offseason. I run for between 30 and 35 minutes every day.
"I feel like I can actually throw harder when I get to the fifth inning," he continued. "I'm not tired at all at that point in the game. I feel like I can throw 100 pitches just about every time I'm out there, and I'm not losing anything on any of my pitches late in games."
He certainly doesn't. According to FanGraphs, Severino led all Major Leaguers with an average fastball velocity of 97.8 mph through mid-July and had thrown 43 pitches in the sixth inning or later that registered at least 99 mph. Boston's Chris Sale, with 14 fastballs clocked at 99 mph or faster in those innings, ranked second.
Severino's heater, which tops off at 101 mph, has no doubt led to his impressive record this season. But having some big league experience under his belt has also helped.
"For me, the regular season is about coming in with my pitches," Severino said. "What I learned from last year and how well I did is that I have to trust my pitches. In order to get deep into games, I have to consistently throw the ball over the plate. I can't waste pitches, and I figured that out last year."
The faith that Severino has had in himself this season -- and his willingness to attack the strike zone -- has produced tangible results. With 138 strikeouts through his first 18 starts, Severino was not only on pace to eclipse his mark of 230 from last season, but he was also ahead of Ron Guidry's pace from 1978, when Gator set the single-season franchise record with 248.
"That's a great record," Severino said. "But it's not something I really think about. Just to be mentioned in the same conversation with Ron Guidry is exciting, but I want to win. That's what he did, and that's why he is still regarded so highly."
Besides having confidence in himself, Severino has taken the mound this season knowing that the Yankees' lineup will give him more runs than he'll probably need.
"We have a great team," he said. "If I'm on the mound and we're losing 2-0, I know that we're going to come back. This team can always score a few runs. I can pitch to batters without worrying about giving up a run or two. The guys around me are a huge reason why I've been able to do what I've done this season."
Severino's humility is matched by his determination to improve. After an up-and-down postseason in 2017, he approached the offseason with intensity, and what he accomplished during the first half of this season was not good enough for him. His goal was to be even better in the second half.
"I want to improve the consistency on my secondary pitches," he said. "My change-up would be the first one. If I can combine my change-up with my other pitches and get it over for strike one a lot of the time, I can be a different pitcher and throw fewer balls in the second half. I walked 51 batters last season, and I do not want to get to 50 this year."
Time will tell whether Severino, who had issued 29 walks through his first 18 starts, will be able to stay under 50. But he has proven that he can throw an effective change-up -- along with an elusive slider -- whenever he wants, making him a vastly different pitcher from the one fans saw at the beginning of his career.
"At first, when I didn't have a good change-up, I was throwing my fastball and slider most of the time," he said. "But now, if my slider isn't working, I can go to my change-up and throw it more than just a few times. I can get through good lineups with my fastball and change-up, and only throw a few sliders. That's been the biggest difference this season."
Of course, there were plenty of games in 2018 when all three of Severino's pitches were working. One of those starts took place on May 2 against the Astros in Houston. On that night, in addition to a full repertoire of Severino's pitches, the Astros had even more to overcome.
"I was still mad about losing to them last year in the postseason and not getting to the World Series," Severino said. "For me, I had to go out there and shut them out and win that game. It was something that I had to do to build my confidence and the confidence of my team."
The 24-year-old did just that, striking out 10 and walking one in shutting out the defending World Series champions in front of a hostile crowd. When contemplating how he has gone from a struggling young pitcher to the staff ace, Severino pointed to two mentors.
"I would say more than anyone else, Larry Rothschild is the reason I have improved so much," Severino said. "Having the opportunity to work with him now for a few years has been important. He really knows how to communicate with his pitchers. Every time I was taken out of a game early, he would talk to me about what I needed to do better and what I was doing well. If I didn't understand something, he would make sure I got it."

Severino's other mentor is a little further removed from the Yankees organization than the team's pitching coach but has nonetheless had a major influence on him. Growing up in the Dominican Republic, Severino looked up to Hall of Famer Pedro Martinez. While dominating competition on the island during his early years, Severino also watched closely as the fellow Dominican pitcher etched his name into baseball lore with the Dodgers, Expos and Red Sox before finishing his career with the Mets and Phillies.
In each of the last two offseasons, Severino has spent time with his idol in the Dominican Republic, and besides living out a dream, the time with Martinez has proven to be valuable for Severino's career.
"He's a nice guy, and that has made the experience of getting to know him special for me," Severino said. "He's also helped me a lot, beginning in 2016. He worked with me on my mechanics more than anything else. He noticed that I was moving my hands right before I threw certain pitches. He told me that veteran hitters were probably picking up on that, and that if I moved less, those good hitters would not know what pitch I was about to throw.
"I realized that he was right," Severino continued. "I had been doing that for my first two seasons. I worked hard on fixing it before the 2016 season. I bought a big mirror, and every day I practiced my wind-up at least 100 times in front of the mirror. When I got to Spring Training, I wasn't moving my hands at all."
This past offseason, Severino's time with his childhood hero was spent reaffirming what he had already learned.
"When we got together this offseason, he told me that the things we worked on last year helped me with the command of my fastball and slider, besides making it harder for batters to know what I was throwing," Severino said. "This time around, he just emphasized that I should keep working on my mechanics so that nothing changes."
As Sabathia had predicted in the vintage sports clothing store, Severino powered the Yankees to victory in his June 26 start in Philadelphia. With his fastball and slider at their peak, Severino rarely went to his change-up over seven innings of work. He didn't give up a run or a walk while striking out nine batters.
"Sometimes when you go to the mound, you feel like it's your night," Severino said after the game. "I was feeling like that as soon as I got here this afternoon. It was my first time pitching here, and I was a little surprised about how small this ballpark is, but right from the beginning, I was commanding all of my stuff and throwing strikes. When you're doing that, you know it's going to be a good game, no matter where you're pitching or who you're facing."
Severino has had those same feelings quite often this season, and it has made his job as enjoyable as ever.
"I'm having a lot of fun this season," he said. "I've been playing this game since I was 8 years old, and I've always loved getting out to the mound and competing. Although I take it seriously now, it's still a lot of fun, especially on nights like this."
When Severino's thoughts shifted from the euphoria of another shutout performance to the foreseeable future -- including his team's chances of winning a championship this season -- his smile was replaced with the determined look that he so often displays on the mound.
"Right now, I'm focused on the next five days and my next start," he said. "I don't really like to look too far in front of that. But I can tell you that it's going to be different this year. We're going to get there. I have faith in my team, and we're going to go all the way this year."
Five days after his gem in Philly, Severino pitched 6 2⁄3 innings against the Red Sox at Yankee Stadium, again not allowing a run. The Yankees won the game in a rout, keeping pace with their archrivals in the standings. With a recent past as great as Severino's and a future as bright as his has the potential to be, it's not hard to imagine a No. 40 pinstriped jersey hanging on a rack next to those of Ripken, Puckett, Schmidt and Jackson someday.