Players / Player profile
KC · P

Stephen Kolek

Age 29 B/T R/R 6′3″, 210 lb USA MLB debut 2024
40-man
  • Kansas City’s roster as it stands #4 starter · 109 IP · 1.0 WAR in the role
  • Injured list Ended 2026 on the 60-day IL: Right flexor strain (since Jul 19)
  • Trade read Available at a price: KC 39% playoff odds; control through 2030.
Keystone Stuff 90 10th pct
2026 fWAR 0.5
Projected 2027 WAR 1.0 at 108 IP · 1.0 in his 2027 role

Pitching · 2026 percentiles

vs. MLB pitchers with 500+ pitches · 837 pitches

Keystone Stuff 90 Keystone Stuff: 90, 10th percentile
Keystone Location 109 Keystone Location: 109, 88th percentile
Keystone Pitching 96 Keystone Pitching: 96, 39th percentile
Run value (xRV) +0.23 Run value (xRV): +0.23, 57th percentile
Strikeout % 15.2% Strikeout %: 15.2%, 5th percentile
Walk % 5.4% Walk %: 5.4%, 94th percentile
Whiff % 19.8% Whiff %: 19.8%, 10th percentile
Chase % 26.8% Chase %: 26.8%, 13th percentile
Fastball velo 94.0 Fastball velo: 94.0, 42nd percentile
Extension 6.2 ft Extension: 6.2 ft, 30th percentile
54.0 IP4.50 ERA4.54 FIP 34° arm

Arsenal & Pitch Lab

Movement normalized to arm side · Keystone Stuff by pitch

−20−20−10−100010102020← Glove sideArm side →Rise (IVB, in) →4SSISLFCCHST
RHP · arm angle 34° · how to read
PitchUseVeloIVBHBStuffLocWhiffxRV/100
Four-seam28% use28%94.213.2+6.48810919%+0.86
Sinker22% use22%93.75.0+14.8931106%+0.13
Slider16% use16%85.6−0.4−3.21019943%+1.24
Cutter12% use12%90.36.5−1.99510321%+0.94
Changeup12% use12%87.12.6+12.18611516%−1.65
Sweeper9% use9%79.9−5.4−14.798889%−1.75

No mix change or new pitch clears its bar. The arsenal is efficient for its shapes.

Most similar pitchers

Pitches like Kolek: same hand, shape, slot and mix

SimilarityPlayerStuff’26 WAR’27 proj2027
68Colin Rea CHC · ’90960.40.4Free agent
66Zebby Matthews MIN · ’00920.71.1—
63Max Scherzer TOR · ’84970.30.1Free agent
60Tomoyuki Sugano COL · ’89840.4−0.1Free agent
58Keider Montero DET · ’00922.51.7Pre-arb

Same-handed pitchers nearest on fastball velocity and shape, arm angle, extension, pitch mix, secondary shapes, Stuff, whiff rate and workload. 2026 regulars only.

Pitch locations · 2026

Where each pitch finishes, by batter side

Four-seam 35%
48% zone
Changeup 19%
31% zone
Cutter 18%
58% zone
Sinker 11%
60% zone
Slider 10%
40% zone

Where each pitch finishes, catcher’s view. The bar marks the batter’s side; the box is an average strike zone. Pitches with 40+ thrown to this side.

Contract & projection

Club control (RosterResource) · Keystone projected WAR

2027 1.0 WAR Pre-arb $780K*
2028 0.9 WAR Arbitration $2.2M*
2029 0.7 WAR Arbitration $4.0M*
2030 0.5 WAR Arbitration $5.5M*

* projected arbitration or minimum salary. Contract Studio →

Minor leagues

MLB Stats API · public box-score data

SeasonLevelLevelTeamAgeGPA / IPPA / IP ·Line
2026AAAAAAOmaha Storm Chasers29519 IP 19 IP · 3.32 ERA · 20.5% K · 4.8% BB
2025AAAAAAOmaha Storm Chasers281146 IP 46 IP · 6.26 ERA · 18.6% K · 6.8% BB
Keystone is an independent portfolio project. It is not affiliated with Major League Baseball or any club. Data: MLB Stats API, Baseball Savant, FanGraphs. Used under their terms for individual, non-commercial use.