Mithrandir Metrics
Player St. Louis Cardinals Refreshed Jun 1 06:00 AM ET
Player profile / St. Louis Cardinals

Riley O'Brien

P profile with live context, projection links, and Mithrandir card history when available.

Cards
0
Modules
0
Live Δ
yes
Club St. Louis Cardinals Position P Roster Active 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 preseason3.78
ERA current pace2.96
ERA rolling p503.52
Observed weight32%
ERA
1.70 2.56 3.52 4.48 5.34
FIP
2.27 2.72 3.23 3.73 4.19
K%
19.4% 21.7% 24.2% 26.7% 29.0%
BB%
4.4% 6.0% 7.8% 9.6% 11.2%
Live percentile strip

Current traits vs projection tick

100th = best in MLB.

2026-06-01
Pitching · percentile strip
BB%3.6%
99 +67 vs proj
Barrel allowed4.4%
87
Fastball velo98.3
97
Hard-hit allowed41.2%
38
K%27.9%
83 +29 vs proj
Whiff%28.6%
85 +27 vs proj
xwOBA allowed0.291
70 +24 vs proj
Mithrandir+

Stuff+ and arsenal context

Stuff+ appears when the current pitch-event scoring artifact includes this pitcher; missing coverage is shown explicitly.

2026-06-01
Mithrandir Stuff+104
69
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 O'Brien, Riley · Live snapshot series; true 50/100 PA windows require PA-level logs LG AVG 0.314 2026-05-17: 0.2512026-05-19: 0.2512026-05-21: 0.2822026-05-23: 0.2822026-05-24: 0.2792026-05-25: 0.2792026-05-26: 0.2792026-05-28: 0.2792026-05-29: 0.2792026-05-30: 0.2792026-05-31: 0.2912026-06-01: 0.291 2026-05-17 2026-06-01 xwOBA allowed MITHRANDIR · CHARTS
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.

4Pitches 2026Season 57%Top usage
ride armside gloveside +Arsenal gap +Shape contrast
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 O'Brien, Riley · Aggregate zone metrics; not pitch-by-pitch locations Edge: 37%37%Zone: 45%45%Whiff: 29%29%Called strike: 15%15%First pitch strike: 49%49%Hard hit allowed: 41%41% 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 O'Brien, Riley · 2026 arsenal snapshot Sinker: 56.7%Sweeper: 29.8%Slider: 12.8%Changeup: 0.7% MIX SI 57%ST 30%SL 13%CH 1% MITHRANDIR · CHARTS
Mithrandir Metrics PITCH MOVEMENT Parameterized Mithrandir chart rendered as SVG for templates and exports. Pitch Arsenal O'Brien, Riley · 2026 arsenal snapshot SI: HB 0.1, IVB 2.0SIST: HB -0.1, IVB 3.6STSL: HB 0.1, IVB 2.3SLCH: HB 1.4, IVB 2.4CH horizontal break IVB MITHRANDIR · CHARTS
PitchUsagePitchesStuff+Status
SI 57.3% 217 106 qualified
SL 42.2% 160 95 limited sample
CH 0.5% 2 75 limited sample
Method note

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

Reference layer

Current snapshot

Age31
Height6' 4"
Weight180 lb
Debut2021-09-28
Live layer

Delta / regression

ERA Δ-1.01
K% Δ+0.049
Mithrandir coverage

Module shelf

ModuleCardsLatestSignal
No Mithrandir card history is available for this player yet.
Projection links / recent games

Available detail

Pitcher Projections 202623.0% K | 3.97 ERAProjection
2026-04-15 vs CLE0 ER / 2 K1.0 IP
2026-04-14 vs CLE0 ER / 1 K1.0 IP
2026-04-08 @ WSH0 ER / 0 K1.0 IP
2026-04-07 @ WSH0 ER / 2 K1.0 IP
2026-04-05 @ DET0 ER / 1 K1.0 IP