KANSAS CITY, Mo. (AP) He looks unassuming as he steps on the mound, the lithe kid with the limber arm. He tugs at his hat, bounces a rosin bag playfully in his hand, toes the rubber and proceeds to throw what can only be described as a blur toward the plate.
The unsuspecting hitter never lifts his bat off his shoulder. The ball smacks the catcher's glove and the radar gun on the outfield scoreboard blinks: 102 mph.
No wonder he's nicknamed ''Ace.''
It doesn't seem natural what Yordano Ventura does. Only the biggest, burliest pitchers are supposed throw triple-digit heat. Certainly not a 6-foot, 180-pound-dripping-wet rookie who signed for $25,000 out of the Dominican Republic and not long ago was playing shortstop.
Yet there he is, standing on the mound at Kauffman Stadium, watching as another failed hitter walks slowly back to his dugout, shaking his head in disbelief.
''That kid's special,'' Orioles star Adam Jones says, ''to say the least.''
And it's no wonder the Royals were concerned when Ventura left Monday night's start against Houston because of elbow discomfort. Ventura departed after Jose Altuve fouled off a pitch in the third inning.
Manager Ned Yost and trainer Nick Kenney went to the mound and Ventura was led off without attempting another pitch.
Ventura will have a MRI on Tuesday. He lasted 2 2-3 innings, giving up five runs and seven hits.
Before his outing Monday night, people were interested how Ventura could throw so hard at his size.
Glenn Fleisig, an expert in medical and mechanical engineering, has been studying pitchers for years at the American Sports Medicine Institute, the nonprofit founded by renowned surgeon Dr. James Andrews. While Fleisig has not examined Ventura specifically, he may be able to explain in general terms what makes the right-hander stand out.
''More than anything it has to do with the timing of the different motions,'' Fleisig says.
''You watch it by the naked eye,'' he continues, ''and it looks like the guy steps, his body moves forward and he throws. But if you do it in slow motion, it's really a sequence of events.
''When a pitcher's stride foot lands, his arm, totally not connected to his leg, has to be at a certain position, and his hips and trunk has to be at a certain position. And if we break these things down to a very small fraction of a second, the best pitchers are sequencing right.''
In science, that sequencing is called a kinetic chain. Ventura's is nearly perfect.
''What a pitcher has to do to maximize his ball velocity is maximize his timing of different body parts,'' Fleisig explains. ''That's not the only thing but it is the most important thing.''
Another important element is what Fleisig calls functional strength.
Even though Ventura is about as husky as a foul pole, the muscles, ligaments and tendons that it takes to throw hard have been honed over the years, and not just by pitching.
Unlike youngsters in America who specialize at a young age, Ventura played shortstop - and other sports - along with pitching as a child, and that developed his musculature into that of a well-rounded athlete.
''His body just figured it out right,'' Fleisig says.
This matters because, while many pitchers throw hard, very few throw as hard as Ventura. And the difference between a 95 mph fastball and one that hits triple-digits is astounding.
Alan M. Nathan, a physics professor at the University of Illinois, has found that a pitch released at 95 mph will cross the plate in about four-tenths of a second, and that each additional mile per hour trims that flight time by about 1 percent.
While that may not seem like much, keep in mind the margin of error for putting the ball in play is about seven milliseconds.
''So if a pitcher throws at 100 mph but the batter perceives the pitch at 98 mph, the batter will swing late by about 8 milliseconds,'' Nathan concludes, ''and that is outside of the margin of error for hitting the ball fair.''
In other words, Ventura makes batters swing and miss a lot.
''I'm thankful I have a good arm,'' Ventura says with a shrug, ''and I'm going to keep working hard to be healthy, but nobody has ever explained to me why I'm able to throw so hard.''
During a September call-up last year, Ventura was clocked throwing a four-seam fastball at 102.816 mph - the fastest thrown by a starter since the PitchFX system began tracking the velocity and trajectory of pitches in every major league ballpark during the 2006 playoffs.
This year, the 22-year-old leads the major leagues in average fastball velocity by a wide margin, ahead of power pitchers such as Stephen Strasburg and Justin Verlander. He had a 2.80 ERA through his first nine starts, with 56 strikeouts in 54 2-3 innings.
While there may be a scientific explanation for the way Ventura brings the heat, Royals general manager Dayton Moore offers another suggestion: ''I think it's God-given,'' he says.
In truth, the reason Ventura throws hard may be a mixture of science and dogma.
''He was throwing hard at 18, 19 years old,'' Royals pitching coach Dave Eiland says. ''That's not something where you can go, `Deliver the baseball this way and you'll throw 100.' It's genetics. It must be God-given, you know?''