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Here’s what happened, in order:
Sources reporting this:
Think of Luke Weaver as a specialist pitcher who comes into the game when the team needs to get outs right now – usually in the later innings when the game is close.
Quick Facts:
IMPORTANT: Baseball Stats Explained Simply
- ERA (Earned Run Average): How many runs a pitcher would give up over 9 innings. Lower is better.
- FIP/xERA/SIERA/xFIP: Fancy math that tries to remove luck from the equation. They look at things the pitcher controls (strikeouts, walks, home runs). All saying the same thing: Weaver has been genuinely good.
- BABIP (Batting Average on Balls In Play): How often hitters get hits when they put the ball in play. .204 is very low – meaning some luck is involved.
- Strand Rate: Percentage of runners left on base (not scoring). 82.8% is high – also suggests some good fortune.
| Stat | What It Means | Weaver’s Number | Is It Good? |
|---|---|---|---|
| ERA | Runs allowed per 9 innings | 1.84 | Excellent |
| FIP | "True" skill level | 2.82 | Very Good |
| xERA | Expected ERA based on quality of contact | 2.84 | Very Good |
| SIERA | Another skill metric | 3.09 | Good |
| xFIP | FIP adjusted for home run luck | 3.50 | Solid |
Bottom line: Even if his tiny 1.84 ERA goes up a bit (it probably will), the underlying skills suggest he’s a legitimately good reliever.
Confirmed:
Still Unknown:
The Pittsburgh Pirates are adding a high-quality relief pitcher in Luke Weaver from the New York Mets. Weaver, 32, is having a career-best season with a 1.84 ERA over 44 innings. While some luck is involved (low BABIP, high strand rate), his advanced metrics (FIP, xERA, SIERA) all confirm he’s pitching well – striking hitters out, avoiding walks, and generating ground balls.
The Mets (47-66) are selling off pieces from a disappointing season. The Pirates get bullpen reinforcement for their playoff push. The only missing piece? What the Mets get back. Stay tuned.
A starter begins the game and tries to pitch 5+ innings. A reliever (like Weaver) enters later, usually for 1-2 innings at a time, in high-pressure situations.
Two luck indicators are very extreme: his .204 BABIP (hitters almost never get hits on balls in play) and 82.8% strand rate (almost all runners he allows get stranded). These usually regress toward average over time.
They’re advanced stats that estimate how well a pitcher actually performed by focusing on what they control (strikeouts, walks, home runs) and removing luck. All four agree: Weaver has been very good, just not historically good like 1.84 suggests.
He’s under control for 2025. He signed a 2-year, $22M deal last offseason. The Pirates get him for the rest of 2024 plus all of next season.
Usually within hours of the main report. Beat reporters for both teams will break the details on social media (X/Twitter) first.