← BackAroldis Chapman
BOS · LHP · 2025
60.3 IP · 228 BF · 917 pitches · 2025 season
HIGH Descriptive — not a forecast
120
Stuff+
99th percentile
110
ABStuff+
99th percentile
112
Pitching+
95th percentile
37.3%
K%
99th percentile
6.1%
BB%
79th percentile
2.23
FIP
95th percentile
Grades describe this season's stuff and run prevention. They are not forecasts: on clean season pairs the model has not beaten naive persistence (RESULTS-MLB §13), so nothing here projects next season.
Percentile rankings
vs 2025 graded MLB pitchers · 60.3 IP · 228 BF · 917 pitches · 2025 season
Stuff
Stuff+120
99th percentile
ABStuff+110
99th percentile
Whiff%32.8%
94th percentile
CSW%37.4%
87th percentile
Results
Pitching+112
95th percentile
RV/100+2.53
99th percentile
FIP2.23
95th percentile
RA/94.62
47th percentile
GB%38.3%
38th percentile
Command
K%37.3%
99th percentile
BB%6.1%
79th percentile
K-BB%31.1%
99th percentile
Velo96.1
99th percentile
How to read these
Each row is his rank, 1 to 99, among all graded MLB pitchers this season; the tick is the median. Green is good for him, red bad, whatever the stat's direction (a low FIP ranks high). Grey circles are descriptive rates with no good direction, and n= in place of a rank means too few events to rank. Grades are descriptive, not forecasts.
Percentile rankings
Raw plate discipline · vs 2025 graded MLB pitchers · 60.3 IP · 228 BF · 917 pitches · 2025 season
Swing & miss
Z-Whf%25.7%
97th percentile
O-Whf%50.7%
80th percentile
Chase%34.7%
92th percentile
Z-Con%74.3%
95th percentile
O-Con%49.3%
80th percentile
SwStr%31.6%
92th percentile
PutAwy%22.7%
88th percentile
Approach
Zone%53.5%
80th percentile
Z-Swg%76.8%
95th percentile, descriptive, no good or bad direction
Swing%57.3%
99th percentile
CS%15.2%
5th percentile
F-Str%59.5%
96th percentile
How to read these
Raw rates with this season's descriptive ranks. Sample-adjusted (shrunk) rankings are not shown yet: the reliability constants behind them were measured on college data and are being re-measured on MLB. Until then a small sample here is a small sample — hover the leaderboard column for its event count.
ArsenalKey columns; every column is on the Arsenal tab
Movement Profile
FF+0.7/+3.5SI+4.8/+2.6SL+3.6/+6.3FS-2.1/+3.0ring = slot expectation ±1σ/2σ · HB mirrored for LHP · descriptive
Release Traits
Height: 6.19 ft (±0.11)
Side: 0.31 ft (±0.17)
Extension: 7.32 ft
Season means; the ± is the SD across his pitches. Per-pitch release plots land in a later wave.
Batted Ball Against
Pitch
N_BIP
GB%
FB%
LD%
PU%
Avg EV
Avg LA
HrdHit%
FF
56
30.4
32.1
25.0
0.0
82.1
32.6
32.1
SI
41
39.0
31.7
22.0
0.0
83.3
25.5
39.0
FS
16
50.0
6.2
25.0
0.0
83.0
17.1
43.8
SL
15
53.3
26.7
20.0
0.0
84.0
16.5
40.0
Every pitch type he threw, ordered by balls in play. Rows under 5 BIP are dimmed rather than dropped — a slider put in play twice is a fact about the slider.
Arsenal
Pitches
4
27th pct
Effective mix
3.5
50th pct
Separation
17.8
27th pct
Shape scatter
3.2 in
65th pct
Velo range
12.7 mph
60th pct
FF · SI · SL · FS
2025 season, 917 pitches; percentiles vs MLB pitchers with 100+ that season. A description of the arsenal, not a grade: none of these predicted next season beyond Pitching+ and his own prior year. For shape scatter a higher percentile is MORE scatter.
Location value
runs per 100 pitches vs league
Total
+0.02
57th percentile
Where he throws
+0.14
83th percentile
Which pitch there
−0.12
11th percentile
Heart35.2%
+148.26/100
Shadow39.1%
+125.76/100
Chase18.0%
−278.14/100
Waste7.6%
−488.14/100
What makes up the total
heart · FB16.5%+0.33
chase · SI6.4%−0.27
chase · FB5.0%−0.25
heart · SI11.7%+0.25
waste · SI2.6%−0.21
11 other locations+0.16
Total+0.02
Pitcher-positive, centred on the 2025 league mean (+0.01 RV/100). Ranks are descriptive: the year-to-year reliability of this mix on MLB has not been measured yet, so no cell is verdict-coloured. His actual run value minus this mix — execution — is deliberately not shown.