Post-IL Return Performance Drag

Overview

This pillar analyzes the historical performance of MLB players immediately following their return from the Injured List (IL). It provides a data-driven edge by identifying when the market overvalues a player's immediate impact, creating opportunities to position on underperformance.

What It Does

The model aggregates performance data from thousands of historical MLB player IL stints, focusing on the first 7-10 games post-return. It segments players by injury type, position, and time missed to calculate an expected 'performance drag'. This reveals how much a player is likely to underperform their baseline stats due to rust or lingering effects.

Why It Matters

Public perception and betting markets often react with simple optimism when a star player returns. This pillar provides a crucial, data-backed counterpoint, highlighting the statistical reality that most players need time to regain their form. This creates a predictable edge for betting against inflated expectations.

How It Works

First, the system flags a player returning from the IL. It then pulls data on their injury type, position, and days missed. Next, it queries a historical database for similarly situated players and calculates their average performance dip in the first week back. Finally, it generates a 'Drag Score' predicting the player's likely underperformance on key stats.

Methodology

A 'Performance Drag Score' is calculated by comparing a player's projected stats (e.g., wOBA for hitters, FIP for pitchers) against the historical average performance of players with similar profiles in their first 25 plate appearances or 30 batters faced post-IL. The model applies weights for injury location (e.g., hand/wrist injuries carry a 1.5x negative weight for hitters) and length of absence (a 1.2% drag is added for each week on the IL, capped at 10 weeks).

Edge & Advantage

This pillar provides a specific, statistical reason to bet the 'under' on player props when the narrative is overly positive, directly exploiting the market's emotional bias.

Key Indicators

• Injury Location & Severity

  high

  Distinguishes between arm, leg, or core injuries, as each has a different historical impact on performance.

• Days on Injured List

  high

  A proxy for 'rust'; longer absences correlate with larger initial performance dips.

• Rehab Assignment Stats

  medium

  Performance in minor league games right before returning, indicating current form against lower competition.

Data Sources

• MLB Stats API

  Provides official pre-injury and post-return player performance statistics.

• RotoWire Injury Reports

  Offers detailed information on injury type, timelines, and player status.

• MiLB.com

  Source for minor league statistics during a player's rehab assignments.

Example Questions This Pillar Answers

• → Will Aaron Judge get a hit in his first game back from a toe injury?
• → Will Clayton Kershaw record over or under 4.5 strikeouts in his first start after returning from the IL?
• → Will Fernando Tatis Jr.'s batting average be above .250 in his first 5 games back from a wrist injury?

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