Guess who has thrown baseball's fastest pitch this year? Nope, guess again

Most of the time, Joe Kelly doesn't have to peek at the radar gun. No, the burn of a baseball's stitches against the tips of his fingers -- "That tug out of your hand when everything is going right," Kelly says -- usually tells him whatever he needs to know about how hard he's throwing.

When it doesn't? When the ball doesn't speak to the Boston Red Sox reliever?

"Oh, you can hear the crowd," Kelly says, prompting eavesdropping closer Craig Kimbrel to utter an "ooooooh!" from a neighboring locker. "That kind of lets you know too."

Few pitchers this season are producing more "oooooohs" -- or "aaaaaaahs" for that matter -- than Kelly. Through Tuesday, he had thrown 51 pitches that registered at least 100 mph, third-most in the majors after St. Louis Cardinals reliever Trevor Rosenthal (63) and New York Yankees closer Aroldis Chapman (57), according to Statcast. Kelly's average fastball velocity was 98.8 mph, also a few ticks behind only that of Chapman and Rosenthal (both 99.3 mph).

"Usually if you hear the crowd get a little bit louder, you know that I've got good velocity that day. But it's not something I try to peek at every time. When you can hit triple digits and strike someone out, that's when it's the most fun."
Joe Kelly

But for the single fastest pitch uncorked this season, nobody -- not even Chapman -- can top Kelly's 102.2 mph flash to Chicago Cubs first baseman Anthony Rizzo in the seventh inning April 28 at Fenway Park.

That's some serious speed -- or as Hall of Fame closer Dennis Eckersley puts it, “high cheddar with some hair.” That's not half-bad for a 28-year-old converted starter with a 3.82 career ERA whose brushes with fame in a half-dozen big league seasons range from a 5 1/3-inning no-decision in Game 3 of the 2013 World Series for the Cardinals to stopping for a selfie on the field with Derek Jeter during the ceremony before No. 2's final game in 2014 to making SportsCenter in February by nailing a full-court shot after a basketball game at Florida Gulf Coast University.

"Going to the pen, in the back of my mind, it's just something that I always knew I'd get more velocity," Kelly says of his potential for triple-digit radar readings. "When I relieved in St. Louis a couple times, I hit 100-101 in Houston one time at the end of a game. So, mentally, I knew I could do it. But I didn't know that I could consistently do it. I'd be lying if I said I did."

In that case, allow Kelly's college coach to say it for him.

WHENEVER DOUG SMITH turns on his television and sees Kelly dial up 100 mph late in a game for the Red Sox, he wonders only what took so long.

Smith had several reasons to use Kelly as a closer at the University of California-Riverside. For one thing, Kelly was primarily an outfielder in high school. For another, he came to college weighing only about 155 pounds. Although Smith recruited Kelly with the intention of turning him into a pitcher, he didn't want to be the coach who blew out Kelly's right arm by overusing him.

Kelly took to closing like a bee to honey. As a freshman, he flashed a mid-90s fastball and notched six saves and a 1.32 ERA in 22 appearances. By the time he was a junior, that heater had climbed into the 97-98 mph range. He finished his college career with 24 saves, a school record.

There was something else about Kelly that caused Smith to continue using him at the end of games, even after he built enough arm strength and a credible three-pitch mix to merit at least a chance at being a starter.

"If you know Joe, he pitches with a little arrogance," Smith says. "I say that positively. I'm calling that a positive trait. To be honest, I thought the personality would really fit at the end of the ballgame, as well as the stuff. The situation wasn't going to get too big for him, and he kind of loved that situation."

Take, for instance, the game that clinched the Big West championship in 2007. Kelly came on to record the final two outs and got so fired up that he began hollering at the opposing dugout.

"Especially in college, every win is so emotional," Kelly says. "I feel like I'm a high-energy guy, so you know, I'd get a save and then yell at the other team and frickin' just talk a bunch of crap. That's what I liked doing, especially coming in as an 18-year-old kid. It was more, I would say, a different vibe as a starter. It kind of fit me."

If that sounds a little nutty, well, it's consistent with most everything else about Kelly.

Kelly once noted in a questionnaire for UC-Riverside's baseball media guide that he is related to prohibition era mobster George "Machine Gun" Kelly, a fun nugget that is pure fiction, at least as far as Kelly knows. Two years ago, in a WEEI radio interview at the Red Sox's annual winter caravan, he predicted that he would win the Cy Young Award -- never mind that he had never before won more than 10 games. Kelly’s post-baseball aspiration: ride around on his skateboard.

Given how little he had actually pitched, it made sense that the Cardinals used Kelly as a starter for him to log as many innings as possible. The longer the Cardinals and later the Red Sox stuck with Kelly in the rotation, despite control problems and other inconsistencies, the more Smith couldn't understand why a decision wasn't made to put him back in the bullpen.

Last season, the Red Sox finally changed Kelly's role. In 31 appearances dating to last September, he has posted a 1.21 ERA with 37 strikeouts and 13 walks in 37 1/3 innings.

"The way the game is evolving, the way bullpen usage is evolving, a guy like him down there that could evolve into your closer or could be a multi-inning guy, boy, ain't that just such a commodity to have?" Smith says. "And let's face it: The fastball's pretty electric, as is the curveball. You only get one at-bat against that, it's pretty good."

KELLY'S ROLE IN the Red Sox bullpen remains undefined.

Until the last week of spring training, Kelly was manager John Farrell's top candidate to pitch the eighth inning. A poor finish to the spring caused him to cede that role to Matt Barnes. Kelly didn't allow a run in 10 appearances in May, and not coincidentally, he has pitched his way back into a high-leverage role, with four of his past six outings coming with the Red Sox tied or leading in the sixth inning or later.

In time, it’s easy to see Kelly as the primary setup man to Kimbrel. Or, given his starter’s pedigree, perhaps Kelly could be a multi-inning weapon who pitches in the highest-leverage situation before the ninth inning.

"Joe has done an outstanding job for us," Farrell says. "I think since the trade [in 2014], I think he's become more aware of himself as a pitcher and what his strengths are and how to best apply [them] inside game situations. I think he's taken to the bullpen, both in terms of accepting his place on the pitching staff and starting to really evolve as a late-inning guy."

For that, Kelly credits a shorter, more compact delivery designed to put less strain on his shoulder. He also has changed the way he prepares. As a starter, he says he was a slave to scouting reports, which filled his head with too much information. As a reliever, he thinks less.

"I kind of got caught up in the starting role, trying to pitch to what the scouting reports say or what I saw on video. It was like, 'Hey, this guy's not good with a changeup with two strikes,' instead of attacking with how I pitch," Kelly says. "Now, coming out of the pen, it's just, 'All right, I'm coming to attack, and this is what I've got, these two or three pitches in a given night.' It's just me doing what I do, where you go out there with the focus and a lot of energy and kind of an F-the-other-team mentality."

It helps to have a 100 mph fastball too, one that can cause 30,000 people to gasp as they look at the radar reading.

"Usually, if you hear the crowd get a little bit louder, you know that I've got good velocity that day," Kelly says. "But it's not something I try to peek at every time. When you can hit triple digits and strike someone out, that's when it's the most fun."

Spoken like a pitcher who might have finally found his calling.