Wilberto Rivera Stars in Jupiter

JUPITER, Fla.—The World Wood Bat Association Championship tournament began on Thursday. The tournament marks the end of the fall season for many top high school prospects, and the event gives prospects an opportunity to improve their draft stock. It’s also the premier tournament for travel baseball, and the top travel programs take the competition seriously.

One prospect who has seen his stock rise in recent weeks is righthander Wilberto Rivera (Carlos Beltran Baseball Academy, Florida, P.R.). Pitching for the Toronto Blue Jays Scout Team, Rivera showed off his rocket arm, pumping fastballs at 93-96 mph and touching 97 mph in his first inning. His fastball velocity ranged from 91-96 in his third inning.

Rivera has a physically imposing frame, with wide, square shoulders and a mature build. Up close, he looks every bit of his listed 6-foot-4, 205 pounds. He has a long arm action with a deep plunge in the back, and has struggled to command the baseball in Baseball America’s previous looks. On Thursday, however, Rivera’s delivery was more in sync and his arm was on time more often than not. Rivera showed promising control of his fastball; in three innings, he struck out six batters. Rivera threw 47 pitches and generated 14 swings and missed with his fastball.

Rivera’s curveball remains a work in progress, but he showed the ability to land it for strikes, and it has the 12-to-6 shape and depth to project as a useable second offering. Because of his size, athleticism and elite fastball velocity and angle, Rivera figures to get a chance to develop as a starting pitching prospect at the next level.

On a damp morning with intermittent showers, Jo Adell (Ballard High, Louisville) set fire to the rain with a mean, two-pitch display in a scrimmage for the Evoshield Canes. Adell is a two-way prospect who appears more likely to be drafted as a position player, but he also brings significant upside to the mound.

In his lone inning of work, Adell threw his fastball at 93-94 and was hit a bit, but he showed off his hard, late-diving breaking ball, which competed in the strike zone at 82-84. He has a chance for two pitches that grade out as at least above-average.

At the plate, Adell went 1-for-6 in two games. He was 0-for-3 with a strikeout in his first game (which Baseball America witnessed), and 1-for-3 with a double, two runs batted in and a walk in his second game, according to Perfect Game.

DROPS FROM JUPITER

• Suiting up for the Braves Scout Team/Ohio Warhawks, outfielder Calvin Mitchell (Rancho Bernardo High, San Diego) continues to prove himself as one of the best pure hitters in the 2017 class. Mitchell is a lefthanded hitter with a loose swing, excellent bat control and a knack for putting the ball in play. He showed the ability to work counts and wait for pitches he could do damage with on Thursday. In two games, Mitchell went 4-for-6. He is committed to San Diego.

• Righthander Boyd Vander Kooi (Skyline High, Mesa, Ariz.) showed promise with a three-pitch mix. He has a loose, projectable arm action to go along with his projectable 6-foot-3, 180-pound frame. Vander Kooi’s fastball worked at 88-91 and touched 92. He is committed to Oregon.

• Righthander Caleb Sloan (Regis Jesuit High, Aurora, Col.) showed plus arm speed. He has a bow-and-arrow type of arm action, cocking his throwing arm up and back as he extends his glove forward. Sloan struggled with timing his release point, but he has potential with a fastball/slider combination. He is committed to Texas Christian.