P | Bats/Throws: R/R | 6' 1" 209 lbs | Age: 21
MLB Pipeline Rank
Giants: No. 11
W L ERA G GS SV IP SO WHIP
2025 2 1 2.86 6 3 0 22 30 1.45
Career Minors 6 3 2.47 40 11 5 102 120 1.25
G W-L ERA IP SO WHIP
2025 6 2-1 2.86 22 30 1.45
Career Minors 40 6-3 2.47 102 120 1.25
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Standard Minor League Pitching Statistics

SeasonTmLGLWLERAGGSSVIPHRERHRBBSOWHIP
2024 ACL Giants ACL ROK 1 1 3.03 19 0 3 32.2 27 15 11 2 16 23 1.32
2025 2 Teams Minors 5 2 2.21 21 11 2 69.1 63 22 17 3 21 97 1.21
2025 ACL Giants ACL ROK 3 1 1.90 15 8 2 47.1 42 13 10 1 10 67 1.10
2025 San Jose Giants CAL A 2 1 2.86 6 3 0 22.0 21 9 7 2 11 30 1.45
ACL Giants ACL ROK 4 2 2.36 34 8 5 80.0 69 28 21 3 26 90 1.19
San Jose Giants CAL A 2 1 2.86 6 3 0 22.0 21 9 7 2 11 30 1.45

Scouting Report

2026

Scouting grades: Fastball: 60 | Slider: 60 | Changeup: 45 | Control: 50 | Overall: 45

Nearly 19 years old when he signed for $10,000 out of Venezuela in July 2023, Martinez made a steady if unspectacular pro debut the following summer. Named Arizona Complex League pitcher of the year when he returned there in 2025, he led the Rookie-level circuit with 67 strikeouts in 47 1/3 innings and would have topped the ACL in ERA (1.90), strikeout rate (35 percent), walk rate (5 percent) and K/BB ratio (6.7) if he hadn't fallen two outs shy of qualifying. He finished his season by contributing to a California League championship at Single-A San Jose.

Martinez's stuff made a jump last season, with his fastball sitting in the mid-90s and reaching 98 mph with armside run, showing carry at times and downhill plane at others. He also added sweeping action to his low-80s slider, giving him a pair of plus pitches. While his upper-80s changeup is too firm and lags behind his offerings, it does flash some interesting fade.

While Martinez lacks physicality at 6-foot-1 and a listed 165 pounds, he's strong and athletic. He gets down the mound well, providing deception via extension and a low release height. He didn't pound the strike zone as much in the Cal League as he did in the ACL, but he should have at least average control.


2025

Scouting grades: Fastball: 60 | Slider: 60 | Changeup: 45 | Control: 50 | Overall: 45

The Giants have had a number of young international pitching prospects emerge in 2025, including Martinez. Signed for just $10,000 out of Venezuela in July 2023, he attracted little attention during his pro debut last summer. He has shown one of the best arms in the Arizona Complex League while repeating the Rookie-level circuit this year.

Martinez's fastball has jumped into the mid-90s this summer and stayed there throughout four-inning stints while topping out at 98 mph with downhill plane and armside run. His low-80s slider is an even better offering, and he can throw it for strikes or use its quality depth to get chases below the strike zone. His changeup is more of a work in progress, a bit too firm in the upper 80s but flashing some interesting fade.

The 6-foot-1 Martinez isn't big but he's strong and gets down the mound well, creating some deception with extension and a low release height. He repeats his delivery well and has been one of the better strike throwers in the ACL. Other teams have taken note and brought him up in trade talks.



Awards




Transactions

Team Date Transaction
03/05/2026 RHP Keyner Martinez assigned to San Francisco Giants Prospects.
07/31/2025 RHP Keyner Martinez assigned to San Jose Giants from ACL Giants.
05/09/2024 RHP Keyner Martinez assigned to ACL Giants from DSL Giants Orange.
07/06/2023 RHP Keyner Martinez assigned to DSL Giants Orange.
07/03/2023 San Francisco Giants signed free agent RHP Keyner Martinez to a minor league contract.