How Do Inherited Runners Affect a Relief Pitcher's ERA?

Bottom of the 7th. Runner on third, one out. The starter gets pulled. You're the reliever. The next batter hits a sacrifice fly. The run scores.

Whose ERA does it hurt? Not yours. The run gets charged to the starter who put that runner on third.

This is the inherited runner rule — and it's why relief pitcher ERAs can be deceivingly low.

Here's exactly how inherited runners affect a relief pitcher's ERA, why the rule exists, and why it makes ERA a flawed stat for evaluating relievers.

The Core Rule: Inherited Runners Don't Affect Your ERA

The inherited runner rule is simple:

This means a relief pitcher can enter with the bases loaded, give up a grand slam, and only be charged with ONE earned run (the batter who homered). The three inherited runners count against the previous pitcher's ERA, not yours.

Why This Rule Exists

The logic makes sense on the surface: You shouldn't be penalized for a situation you didn't create.

If a starter loads the bases with nobody out, then gets pulled, the reliever enters a disaster scenario not of their making. Charging all subsequent runs to the reliever would be unfair.

The previous pitcher created the mess. They should be held accountable for it.

That's the theory. In practice, it creates massive distortions in how we evaluate relief pitchers.

How The Inherited Runner Rule Works: Examples

Let's work through scenarios to see exactly how inherited runners affect ERA:

Why This Makes Relief Pitcher ERAs Misleadingly Low

The inherited runner rule systemically lowers relief pitcher ERAs. Here's why:

1. Setup Men Escape Damage

Setup relievers often enter with runners on base. They're brought in specifically for high-leverage situations — bases loaded, runners in scoring position.

When they allow those runners to score, it doesn't hurt their ERA. All the damage gets charged to someone else.

A setup man can have a sparkling 2.50 ERA while constantly allowing inherited runners to score. The box score makes him look great. Reality? He's failing in his primary job.

2. Closers Get Protected

Closers typically enter clean innings (no runners on base). They don't inherit runners often.

But when they DO inherit runners — say, bases loaded, one out in the 9th — and blow the save, their ERA often stays low because the inherited runs don't count.

This makes closers' ERAs look better than setup men's ERAs, even when the setup man is actually more effective.

3. The "Vulture" Closer

Some closers built careers on low ERAs by entering games with inherited runners already in scoring position, getting one out, and escaping without allowing their own baserunners.

Their ERA looks elite. But they're not dominating — they're benefiting from a scoring quirk.

4. Starter vs Reliever ERA Gap

Relievers league-wide have lower ERAs than starters. Part of this is real (relievers throw max effort, face fewer batters). But part is the inherited runner advantage.

Starters own all their baserunners. Relievers share responsibility or avoid it entirely.

The Infamous Examples

Baseball history is full of moments where the inherited runner rule created absurd outcomes:

2014 NLDS: Drew Storen Gets Lucky

Jordan Zimmermann dominated for 8.2 innings. A borderline ball-four call put a runner on first with two outs.

Manager pulled Zimmermann. Drew Storen entered.

Storen gave up a single (runner to third) and a double (run scores). But he escaped the inning when a runner was thrown out at the plate.

Final line:

• Zimmermann: 8.2 IP, 1 ER (ERA takes a hit for a walk that barely mattered)
• Storen: 0.1 IP, 0 ER (ERA stays clean despite giving up the hits that scored the run)

Zimmermann did all the work. Storen did most of the damage. But Zimmermann's ERA suffered while Storen's didn't.

The Classic Closer Scenario

Closer enters the 9th with a one-run lead. Bases loaded, two outs.

First pitch: Grand slam. Game over.

Closer's line: 0.0 IP, 1 H, 1 ER (infinite ERA for this appearance, but only 1 run instead of 4)

The closer blew a save in spectacular fashion but gets charged for only one run. The setup man who loaded the bases gets three runs charged to his ERA.

Who really failed more? Arguably the closer. But the stats don't reflect that.

Better Stats for Evaluating Relievers

Because ERA is flawed for relievers, analysts use alternative metrics:

1. Inherited Runners Scored Percentage (IRS%)

What it measures: What percentage of inherited runners score while you're pitching?

How to use it:

• Elite: Under 25% (3 out of 4 inherited runners are stranded)
• Good: 25-35%
• Average: 35-45%
• Poor: Above 45%

This stat directly measures a reliever's effectiveness in the situations they actually face.

2. FIP (Fielding Independent Pitching)

What it measures: ERA based only on strikeouts, walks, hit-by-pitches, and home runs (things the pitcher controls).

Why it's better for relievers: Removes inherited runner bias. Treats all baserunners equally.

A reliever with a 2.50 ERA but a 4.00 FIP is probably getting lucky with inherited runners. A reliever with a 3.50 ERA but a 2.50 FIP is probably unlucky.

3. RE24 (Run Expectancy)

What it measures: Change in run expectancy based on game situations.

Entering with bases loaded, nobody out = high run expectancy. Getting out of it without allowing runs = big positive RE24.

This stat captures true impact better than ERA for relievers.

4. Context-Neutral Stats

Look at:

• K/9: Strikeouts per nine innings
• BB/9: Walks per nine innings
• K/BB: Strikeout-to-walk ratio
• Hard contact rate: Percentage of batted balls hit hard

These metrics don't care about inherited runners. They measure actual skill.

Why The Rule Won't Change

Despite its flaws, the inherited runner rule isn't going anywhere. Here's why:

1. Tradition

Baseball loves its traditions. The inherited runner rule has existed for over a century. Changing it would break historical comparisons.

2. Simplicity

The current rule is easy to understand: Your runners = your responsibility. Someone else's runners = their responsibility.

Proposed alternatives (splitting runs based on probability, shared responsibility models) are more complex and harder for casual fans to follow.

3. No Perfect Solution

Every alternative has problems. Split responsibility based on run expectancy? Suddenly you're charging pitchers with 0.72 runs or 0.38 runs. That's confusing.

Charge the reliever for allowing inherited runners to score? Now you're penalizing relievers for situations they didn't create.

The current system isn't perfect, but it's the clearest imperfect option.

What This Means For You

If You're Evaluating Relievers

Don't rely on ERA alone. A 2.00 ERA doesn't automatically mean a reliever is elite. Check:

• IRS%: Are they stranding inherited runners?
• FIP: Does their ERA match their FIP?
• K/BB: Do they have good command and miss bats?
• Leverage situations: When do they pitch (high-leverage or mop-up duty)?

If You're A Relief Pitcher

Understand that your ERA might look better than your actual performance. Don't get complacent.

Track your own inherited runner stats. If you're constantly allowing inherited runners to score, your ERA might be low but you're not doing your job.

If You're A Starter

Know that your ERA can get hammered by incompetent relievers. You load the bases with two outs, get pulled, and the reliever gives up a grand slam? All three inherited runs hurt your ERA.

This is why some aces insist on finishing innings before exiting games. They don't want to leave their ERA in someone else's hands.

The Bottom Line

How do inherited runners affect a relief pitcher's ERA?

They don't — and that's the problem.

Inherited runners who score are charged to the pitcher who put them on base, not the reliever who allowed them to score. This creates systematically low ERAs for relief pitchers, especially setup men and closers who frequently enter with runners already on base.

The result:

• Relievers can have low ERAs while constantly allowing inherited runners to score
• ERA doesn't measure a reliever's actual effectiveness in high-leverage situations
• You need additional stats (IRS%, FIP, RE24) to truly evaluate relievers

The fix:

Use ERA as one data point among many. For relievers, inherited runner statistics, FIP, strikeout-to-walk ratios, and leverage index matter just as much — if not more — than ERA.

The inherited runner rule isn't changing. But your evaluation methods should account for its limitations.

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