Mithrandir Metrics
Pitcher projection 2026 Refreshed Jun 1 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
--
Team BOS Archetype Balanced reliever 2 Age 29 Status Healthy / active roster
Rolling projection

Preseason / current pace / Bayesian update

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

2026-06-01
ERA preseason3.74
ERA current pace4.15
ERA rolling p503.82
Observed weight19%
ERA
2.12 2.93 3.82 4.71 5.52
FIP
2.86 3.28 3.74 4.21 4.63
K%
17.1% 20.1% 23.5% 26.8% 29.8%
BB%
5.1% 6.5% 8.2% 9.8% 11.2%
Current percentile strip

Actual percentile with projection tick

100th = best in MLB.

2026-06-01
Mithrandir+

Stuff+ and arsenal context

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

2026-06-01
Mithrandir Stuff+108
92
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.

5Pitches 2026Season 51%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

0 snapshots
No chart yet

No Live State xwOBA snapshots are available for this player.

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: 57%57%Whiff: 22%22%Called strike: 17%17%First pitch strike: 55%55%Hard hit allowed: 45%45% 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: 51.2%4-Seam Fastball: 28.4%Sweeper: 17.2%Curveball: 2.8%Split-Finger: 0.5% MIX FC 51%FF 28%ST 17%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 FC: HB -0.1, IVB 2.0FCFF: HB 0.0, IVB 1.0FFST: HB -0.5, IVB 2.9STCU: HB 0.4, IVB 4.1CUFS: HB -1.1, IVB 2.7FS horizontal break IVB MITHRANDIR · CHARTS
PitchUsagePitchesStuff+Status
FC 51.3% 77 106 limited sample
FB 30.0% 45 110 limited sample
SL 16.0% 24 96 limited sample
CB 2.7% 4 108 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

No Live State delta is available for this player yet.

Projection table

Point projection and range

MetricPointRangeHalf-width
Innings36.4----
Batters Faced149----
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%