Mithrandir Metrics
Pitcher projection 2026 Refreshed Jul 17 06:00 AM ET
Pitcher projection / BOS · 2026

Slaten, Justin

Late-inning arm with usable miss-bat shape

Primary
22.2% K%
Range
15.6% to 30.8%
Live Δ
yes
Team BOS Archetype Balanced reliever 2 Age 29 Status Healthy / active roster
At a glance

Season percentile report

The headline weighs outcome stats (xwOBA, barrels); each bar averages its full strip group below. 100 = best in MLB.

2026-07-17
56
Pitching
percentile
Pitching9 metrics
51
Arsenal4 metrics
74
Rolling projection

Preseason / current pace / Bayesian update

Rolling bands shrink current-season signal toward the preseason prior until the sample earns more weight.

2026-07-17
ERA preseason3.74
ERA current pace5.64
ERA rolling p504.35
Observed weight32%
ERA
2.82 3.55 4.35 5.16 5.88
FIP
2.84 3.22 3.64 4.06 4.43
K%
19.0% 21.6% 24.4% 27.3% 29.9%
BB%
4.8% 6.0% 7.4% 8.8% 10.0%
Current percentile strip

Actual percentile with projection tick

100th = best in MLB.

2026-07-17
Pitching · percentile strip
WHIP1.52
16
ERA5.64
15
BB%7.1%
74
K%29.2%
90 +43 vs proj
xwOBA allowed0.277
85 +34 vs proj
Barrel allowed8.3%
40 -23 vs proj
Fastball velo96.7
83
Hard-hit allowed44.4%
15
Whiff%22.5%
46 -19 vs proj
Mithrandir+

Stuff+ and arsenal context

Stuff+ appears when the current pitch-event scoring artifact includes this pitcher; Arsenal Decomposition remains descriptive support under Stuff+.

2026-07-17
Cutter Stuff+106
88
Fastball Stuff+108
88
Mithrandir Stuff+107
87
Slider Stuff+99
32
Optimization map

Arsenal optimization map

Pitch-shape context from this pitcher’s current arsenal snapshot. Hover a pitch to inspect usage, movement, and bat-missing context.

6Pitches 2026Season 45%Top usage
ride armside gloveside +Arsenal gap +Shape contrast
Rolling form chart

xwOBA allowed snapshot line

Live snapshot series; true 50/100 PA windows require PA-level logs

12 snapshots
Mithrandir Metrics ROLLING XWOBA LINE Parameterized Mithrandir chart rendered as SVG for templates and exports. season=2026 Rolling xwOBA allowed Slaten, Justin · Live snapshot series; true 50/100 PA windows require PA-level logs LG AVG 0.314 0.277 2026-07-06: 0.2922026-07-07: 0.2862026-07-08: 0.2862026-07-09: 0.2802026-07-10: 0.2802026-07-11: 0.2752026-07-12: 0.2752026-07-13: 0.2772026-07-14: 0.2772026-07-15: 0.2772026-07-16: 0.2772026-07-17: 0.277 2026-07-06 2026-07-17 xwOBA allowed MITHRANDIR · CHARTS
Zone profile

Aggregate zone heatmap

Aggregate zone metrics from seasonal Statcast leaderboards.

Mithrandir Metrics ZONE HEATMAP Parameterized Mithrandir chart rendered as SVG for templates and exports. season=2026 Pitch Zone Profile Slaten, Justin · Aggregate zone metrics; not pitch-by-pitch locations Edge: 37%37%Zone: 53%53%Whiff: 22%22%Called strike: 18%18%First pitch strike: 49%49%Hard hit allowed: 44%44% Dashed border = aggregate mixed-batter zone proxy MITHRANDIR · CHARTS
Pitch arsenal

Usage mix, movement map, and Stuff+ composition

2026 pitch-level arsenal aggregates; current season takes over after 100 tracked pitches across at least 2 pitch types. Descriptive pitch-type Stuff+ composition. Not a promoted predictive metric.

2026
Mithrandir Metrics PITCH ARSENAL DONUT Parameterized Mithrandir chart rendered as SVG for templates and exports. Pitch Arsenal Slaten, Justin · 2026 arsenal snapshot Cutter: 44.8%4-Seam Fastball: 26.7%Sweeper: 16.9%Sinker: 8.8%Curveball: 2.6%Split-Finger: 0.2% FC45% · 93 mphprimary pitch FC 45%FF 27%ST 17%SI 9%CU 3%FS 0% MITHRANDIR · CHARTS
Mithrandir Metrics PITCH MOVEMENT Parameterized Mithrandir chart rendered as SVG for templates and exports. Pitch Arsenal Slaten, Justin · 2026 arsenal snapshot 15″30″45″60″ Cutter: 45% usage, 0″ horizontal break, 23″ drop, 93.1 mphFC93 mph4-Seam Fastball: 27% usage, 0″ horizontal break, 12″ drop, 96.5 mphFF97 mphSweeper: 17% usage, 4″ horizontal break, 35″ drop, 85.9 mphST86 mphSinker: 9% usage, 7″ horizontal break, 14″ drop, 97.2 mphSI97 mphCurveball: 3% usage, 5″ horizontal break, 52″ drop, 84.3 mphCU84 mphSplit-Finger: 0% usage, 13″ horizontal break, 32″ drop, 87.6 mphFS88 mph less drop ↑ more drop ↓ · horizontal break ↔ · dot size = usage · break incl. gravity MITHRANDIR · CHARTS
PitchUsagePitchesStuff+Status
FC 46.5% 105 106 limited sample
FB 30.1% 68 108 limited sample
SL 15.9% 36 99 limited sample
SI 4.0% 9 95 limited sample
CB 3.5% 8 101 limited sample
Method note

Renamed from the attempted Kirby Index after audit; true Kirby requires release-angle trajectory data.

Model read

Projection notes

1
templated note
Volume stays relief-shaped even when the bat-miss traits are strong.
pitcher
2
templated note
Primary mix entering the season: 4-Seam Fastball 36%, Cutter 33%, Curveball 18%.
pitcher
Live context

Current-season signal

ERA Δ+1.85
K% Δ+0.070
Sample25.0 IP
Projection table

Point projection and range

MetricPointRangeHalf-width
Innings35.9----
Batters Faced147----
K%22.2%15.6% to 30.8%+/- 7.6%
BB%7.6%4.0% to 11.2%+/- 3.6%
Whiff%24.9%19.5% to 32.1%+/- 6.3%
HR/91.060.45 to 1.83+/- 0.69
xwOBA Against0.3120.254 to 0.355+/- 0.051
Barrel% Allowed6.9%2.9% to 10.8%+/- 4.0%
ERA3.792.29 to 6.35+/- 2.03
FIP3.752.75 to 4.87+/- 1.06
WHIP1.2300.876 to 1.545+/- 0.334
Platoon / Shape
vs LHH

174 career BF

xwOBA0.273
K%18.9%
BB%6.7%
Barrel5.2%
vs RHH

207 career BF

xwOBA0.262
K%19.1%
BB%4.3%
Barrel6.4%