San Francisco Giants Breakout MLB Prospects Entering 2024

Breakout Prospects

Joe Whitman, LHP

Preseason rank: 14
BA Grade: 45. Risk: High.

Track Record: In a draft class notable for its lack of quality lefthanders, Whitman stood out as the best southpaw available from the college ranks. In three years at Kent State, he established himself as a quality prospect who got plenty of whiffs and pounded the strike zone. San Francisco selected him with its second-round supplemental pick and signed him for $805,575. He reached Low-A in his first pro test and made six appearances between the Arizona Complex League and the California League. 

Scouting Report: Whitman has excellent arm speed and works from a low slot with a three-pitch mix. His repertoire is fronted by a low-90s fastball with tailing action. The pitch peaked at 96 mph. His best offspeed is a sharp slider in the low-80s. The pitch has two-plane break and spin rates around 3,000 rpm. Those qualities make it effective against both lefthanders and righthanders. He finishes his mix with a changeup that sits in the mid 80s and flashed average potential, especially during his time in the Cape Cod League. Bringing the changeup to its ceiling will be a fulcrum in his career. If he can get it there, he’ll have a chance to fit in the back of a rotation. He should have above-average control and did a good job pounding the strike zone in his professional outings.

The Future: Whitman should reach High-A Eugene in his first full season. If his changeup improves, he has a ceiling as a No. 4 starter. If not, he could be an effective left-on-left reliever.

BA Grade: 50/High

Scouting Grades
Fastball: 55. Slider: 60. Changeup: 50. Control: 55.

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Onil Perez, C

Preseason rank: 17
BA Grade: 45. Risk: High.

TRACK RECORD: Perez was signed for $200,000 out of the Dominican Republic in 2019 as part of the same class that also brought shortstop Aeverson Arteaga into the fold. He, too, had to wait until 2021 to make his official professional debut. He spent his first two seasons in the complex leagues before splitting his 2023 season between Low-A San Jose and High-A Eugene.

SCOUTING REPORT: Perez’s calling card is his excellent defense. He’s a quick mover behind the dish who mostly does an excellent job blocking and receiving but could stand to be a shade more consistent in both departments. His arm is a double-plus showpiece that regularly produces pop times in the 1.9-second range, and his arm strength would play up even further with a shortened throwing stroke. Perez makes plenty of contact—he struck out just 38 times in 331 plate appearances—but has yet to show much impact at all. His 90th percentile exit velocity (97.2 mph) was well below-average for his level, and he has just four home runs in 636 career plate appearances. Part of this can be attributed to the fact that while he does an excellent job hitting pitches in the zone, he tends to chase a bit too much and makes weak contact. His open stride also creates holes on the outer half of the plate. Perez is a solid athlete who runs well for a catcher. He also earns high marks for his leadership and the way he works with pitchers.

THE FUTURE: Even with further improvement, Perez is not likely to be a factor offensively. Instead, he has a ceiling as a defense-first regular on a second-division club or a strong backup on a contender.

Scouting Grades
Hitting: 40. Power: 30. Run: 40. Fielding: 60. Arm: 70.

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Trevor McDonald, RHP

Preseason rank: 19
BA Grade: 40. Risk: High.

TRACK RECORD: McDonald was the Giants’ 11th-round pick in 2019. They drafted him from a high school in Alabama and signed him for $800,000, the highest bonus in the round and the third-highest figure in San Francisco’s class. McDonald pitched well in 2022 but really broke out in 2023, when he dominated at High-A Eugene and earned a spot on the 40-man roster.

SCOUTING REPORT: McDonald works with a pair of fastballs and a pair of breaking balls. He added strength to his frame and saw his four- and two-seam fastball each average around 94 mph and peak at 98. He used the two-seamer most frequently, which helped him post a groundout-to-flyout ratio of more than 4.5-to-1. He backs the fastballs with a slider and a curveball. He deployed both at a near-equal rate. The low-80s curveball is the superior offering. It’s a potentially plus pitch with high spin, deep break and rates of miss and chase that grade out as nearly double-plus. McDonald’s slider is a mid-80s offering that gives hitters an extra option to consider. He has potentially plus control as well.

THE FUTURE: McDonald’s biggest test will come in 2024, when he’ll move to Double-A Richmond. He has a chance to start but could be a dynamic weapon out of the bullpen thanks to his nasty sinker.

Scouting Grades
Fastball: 65. Slider: 40. Curveball: 60. Control: 60.