Players / Player profile
SF · SS

Christian Koss

Age 28 B/T R/R 6′1″, 185 lb USA MLB debut 2025
40-man
  • San Francisco’s roster as it stands on the 40-man, off the 26-man (call-up depth)
xwOBA .241 wOBA .269
2026 fWAR 0.0
Projected 2027 WAR 0.3 Keystone Marcel+ at 330 PA

Hitting · 2026

221 PA: percentiles need 300+, so values only

xwOBA .241 xwOBA: .241
Swing decisions −1.67 Swing decisions: −1.67
Contact value −2.19 Contact value: −2.19
Bat speed 69.0 Bat speed: 69.0
Squared-up / swing 18% Squared-up / swing: 18%
Blasts / swing 4% Blasts / swing: 4%
EV90 100.6 EV90: 100.6
Barrel % 4.0% Barrel %: 4.0%
Chase % 39.5% Chase %: 39.5%
Zone contact 79.9% Zone contact: 79.9%
Strikeout % 26.7% Strikeout %: 26.7%
Walk % 4.1% Walk %: 4.1%

Platoon splits · swing path

By pitcher handedness

vsPAwOBAxwOBAK%BB%ChaseDecisionsContact
LHP68.274.20526%3%41%−1.40−3.22
RHP153.267.25727%5%39%−1.80−1.62
Attack angle
10.1° (57% in 5–20°)
Attack direction
+3.1°
Swing length
7.1 ft
Fast-swing rate
5%
Pull-air %
12.6%
Hard-hit %
26.9%
Slash · wRC+
.217/.257/.305 · 58

Zone map · 2026

Where he does damage, and where to pitch him

+1.3−2.9+2.8−0.6−0.5+0.2−0.3−0.8−2.0+0.6−0.9+1.8−4.0−2.2+0.4−0.4+3.9+1.5−0.8−0.6−0.4−0.9−2.6−1.3−1.4RHB

Does the most damage down and in (+3.9 vs. league per 100; 1.8 standard errors on 20 pitches, inside the noise for the best of nine cells).

Weakest middle-middle (−4.0), but only 1.8 standard errors from average on 55 pitches: no in-zone spot to attack yet.

Runs per 100 pitches vs. an average RHB: better · worse. Catcher’s view · 704 pitches · faded cells are within one standard error of average. A spot is called only when it is farther from average than the best or worst of nine average cells gets 95% of the time (set from the league’s own pitches: about 3 standard errors above, 2 below).

Most similar hitters

Swings like Koss: bat path, contact quality and approach

SimilarityPlayerxwOBA’26 WAR’27 proj2027
67José Caballero NYY · ’96.2791.31.5Arb
53Andrés Giménez TOR · ’98.2762.81.9Signed $23.6M
53Ceddanne Rafaela BOS · ’00.2884.13.0Signed $3.8M
46Trevor Story BOS · ’92.2480.20.8Signed $25.0M
46Nathan Church STL · ’00.2840.40.6Pre-arb

Nearest neighbours on bat speed, swing length, attack angle, squared-up and blast rates, EV90, barrels, pull-air, chase, zone contact, K% and BB%. 2026 regulars only.

Fielding

2027 rating at every position he can play · OAA by position · range by direction · tools. Same engine as the Fielding Lab and the Winter Plan.

2027 rating by position · best fit first, on the total with the position’s worth
SS −0.9 +6.6
2B +0.5 +3.0
3B +0.7 +0.2
Outs Above Average by position
SeasonPosOAARangeArm, DPRunsBatters
20262B000.00.0133
20263B+2+1−0.1+0.9679
2026SS00−0.3−0.31,489
2025SS−1−1+0.1−0.9139
20253B00+0.2+0.2294
20252B00+1.1+1.11,430

Runs = range plus his arm and double-play runs spread over his positions by outs (Fielding Run Value, from 2023): what the rating counts.

Range by direction (OAA at SS)
2026 · SS In (charging) +2Back +1Toward 3B line −1Toward 1B line 0vs. RHH +1vs. LHH +1
Tools (percentile; arm among SSs)
Arm at SS 82.7 mph · 41st
Sprint speed 29.0 ft/s · 91st
Zone rating (Keystone expected outs)
SeasonZoneBallsOuts vs. exp.
2026SS146+1.6
20263B60+2.7
20252B162+6.7

The zone rating counts every ball hit to his part of the field while he played there, his club’s positioning included; Savant OAA uses his actual starting spot and is the better individual grade. They agree best in the outfield. See the model card.

Compare in the Fielding Lab →

Contract & projection

Club control (RosterResource) · Keystone projected WAR

2027 0.3 WAR —
2028 0.1 WAR —
2029 −0.2 WAR —
2030 −0.5 WAR —

Contract Studio →

Minor leagues

MLB Stats API · public box-score data

SeasonLevelLevelTeamAgeGPA / IPPA / IP ·Line
2026AAAAAASacramento River Cats28310 PA 10 PA · .444/.500/.778 · 1 HR · 10.0% K · 0.0% BB
2026ROKROKACL Giants28519 PA 19 PA · .389/.421/.556 · 1 HR · 10.5% K · 5.3% BB
2025AAAAAASacramento River Cats27627 PA 27 PA · .296/.296/.481 · 1 HR · 22.2% K · 0.0% BB
2025ROKROKACL Giants2713 PA 3 PA · .667/.667/.667 · 0 HR · 0.0% K · 0.0% BB

ABS challenges · 2026

Baseball Savant

As batter 75% 3/4 won · +0.1 runs
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.