COMPTON, Calif. -- On a baseball field filled with some of the best local prospects in the Class of 2018, one player looked out of place at first glance. But upon further review, Roc Riggio certainly belonged.
Riggio is just 15 years old and a freshman at Chaminade High School in Simi Valley, Calif. Listed at 5-foot-9 and 160 pounds, Riggio is used to defying expectations on the baseball diamond. He's already committed to UCLA, so working out alongside bigger, stronger and older players didn't faze him.
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"I think it's great," Riggio said. "It pushes me. It's a challenge. When I'm with the younger guys, we're all at an equal level, but when I'm up here it's like, 'All right, these guys are bigger than me, I'm the smallest guy on the field.' But height doesn't measure heart, so I'm going to go out there and give it my all and it's going to be fun."
Riggio was one of 43 high school prospects from California, Arizona, Hawaii and Illinois invited to participate in Major League Baseball's Prospect Development Program (PDP) Premier event on Sunday. The PDP is a joint venture between MLB and USA Baseball crated to identify and develop teenage prospects leading up to the 2018 and '19 Drafts.
"It gives the kids an opportunity to show their skills in front of all the scouts and it's beneficial for everyone," one scout said. "It's an opportunity for these kids and they can mingle and meet scouts and crosscheckers for the first time."
All of the prospects went through a variety of tests, with an athletic assessment including a broad jump, vertical leap, 30-yard dash and agility drills. They also had performance vision screening, infield/outfield practice and wood-bat batting practice with a swing analysis. The workout ended with an eight-inning game.
"We're just trying to see the tools," the same scout said. "See how the guy competes against better competition. That's one of the most important things about this event is you've got better pitchers throwing against better hitters. So that gives the scout a better feel for what he can do."
Riggio won't be draft-eligible until 2021, but every opportunity to showcase his skills in front of pro scouts is invaluable to him and evaluators. He's a capable catcher, with the talent to pitch and play the outfield.

"I've got plenty of time to keep an eye on him," the scout said. "The kid threw real well from the outfield and struck the ball real well in batting practice. His coach Frank told me about him months ago, he said, 'You're going to be wanting to see this kid.' So I've already got that kid's name down."
All told, over 100 pro scouts and college coaches were in attendance Sunday, not including Astros reliever and SoCal native Chris Devenski, who stopped by to watch for a few minutes before heading to a back field for long toss.
Here's a look at some of the top performers from Sunday's PDP:
Osiris Johnson, SS/2B, Encinal High School (Alameda, Calif.)
Johnson participated in his second PDP, and he impressed evaluators with his athleticism and slick fielding. Johnson is the second cousin of longtime big league shortstop Jimmy Rollins. A scout said Johnson has a chance to "be a special athlete." He's committed to Cal State Fullerton.
Wes Scott, RHP/3B, Woodcrest Christian High School (Riverside, Calif.)
Scott was dominant on the mound in a scoreless inning, and he sat 91-94 mph with his fastball. "He's got a really good arm," a scout said. A junior in the class of 2019, Scott is committed to Vanderbilt University.
Brandon Dieter, SS/RHP, South Hills High School (West Covina, Calif.)
Dieter pitched a scoreless inning capped off with a swinging strikeout on a breaking ball. He sat 86-87 mph with his pitches. Dieter was part of USA Baseball's 18U National Team last summer.
Cole Winn, RHP/1B, Orange (Calif.) Lutheran High School
Winn didn't need to play in the game to impress the talent evaluators, who are quite excited he's recently moved to Southern California from Colorado. Winn is ranked No. 42 on MLB Pipeline's Top 50 Draft Prospects list, making him the highest-ranked prospect at Sunday's PDP.
Preston Hartsell, OF, Corona del Mar High School (Newport Beach, Calif.)
Hartsell wowed the crowd during batting practice, showcasing his raw power. Some scouts figured Hartsell hit balls over 450 feet during BP. Evaluators say he had the "best raw power" at Sunday's PDP, though Hartsell still needs to get more comfortable facing breaking balls and offspeed pitches. He's committed to USC.
Micah Bello, OF, Hilo (Hawaii) High School
Bello traveled all the way from Hawaii, and he stood out during the game. Bello ripped a two-run triple to the right-center-field gap, racing around the bases and arriving at third standing up. "There's a lot of interest in him," one scout said. Bello is committed to Saint Mary's.