SF Giants top prospects: No. 12 — RHP Blake Rivera
Highest Level: Class-A (Augusta)
Acquired: Draft (2018)
Future-Value Grade: 40+
Blake Rivera, Kervin Castro, and Gregory Santos all have similar profiles. If I had the chance to select any of the three, I’d probably select Rivera last. However, since he remains the only one of the trio that will get another chance to start, he ranks higher for the time being. Rivera has big-time stuff that is nearly ready to play in the back of a big-league bullpen, but smooth mechanics and a sturdy 6’4”-220 frame leave room to believe he could become a mid-rotation starter.
Rivera’s best and most consistent pitch is his 12-6 curveball. Scouts are split on whether it projects as an above-average or plus offering. The pitch has an elite spin-rate with the sharp downward break that the Giants front-office has prioritized in recent years. His changeup oscillates wildly from a virtually unthrowable pitch to a 45-grade offering.
Ultimately how well Rivera harnesses his secondary pitches will determine whether he can stick in the rotation. If he can, how well his fastball plays will determine what his ceiling is. Rivera’s fastball can sit from 94-96 mph and touch 98 mph. That velocity combined with effective cut and a high 2600 RPM spin-rate allows it to play up as a potential 65-grade pitch. However, Rivera has struggled to maintain velocity deep into his starts, often seeing his fastball sitting from 90-94 mph by the third inning. He could still be a back-end starter with lower velocity and better command, but he’ll almost assuredly be moved to the bullpen before he gets that opportunity.
Given how quickly the Giants have been to move Castro and Santos to the bullpen, there’s good reason to believe Rivera has a short window to prove he can have success as a starter. If he fails to move the needle, he could quickly find himself in the Giants bullpen mix. Otherwise, he could have a legitimate case to be the best starting pitching prospect in the farm system if he begins showing better command of his changeup and ability to hold his fastball velocity deeper into games.