← The Casual Fan's Glossary · MLB
baseball.
Baseball is slow, and that's a feature — there's time between pitches to actually know what's going on. These are the terms that show up most in conversation.
RBI (run batted in)
Credit a batter gets when their at-bat makes a run score for their team. Get a hit that drives a teammate home? That's 1 RBI. Hit a home run with two runners on? That's 3 RBIs. The cleanest stat for “this player drove offense today.”
When the broadcast lists who's “leading the team in RBIs,” they mean who's been clutch.
The count
How many balls and strikes the batter has, said as “balls-strikes.” A 3-2 count means three balls and two strikes — one more ball walks them to first, one more strike is an out. Every at-bat is a tiny chess game inside this number.
Announcers say “full count” — that's 3-2, the highest tension before the pitch.
Walk-off
A hit (or walk, or anything else that scores a run) that ends the game in the bottom of the final inning, with the home team winning. Called a walk-off because everyone literally walks off the field — the game is over the moment the run scores.
Walk-off home runs are baseball at its loudest. If you hear the entire stadium go up at once, this is what happened.
No-hitter
When a pitcher goes the entire game without giving up a single hit. Extremely rare — usually a few per season across all of MLB. Even rarer: a “perfect game,” where nobody even reached base.
After the 6th inning of a no-hitter, baseball superstition says you don't mention it out loud. Watch broadcasters dance around the words.
Double play
A defensive sequence that gets two outs on one batted ball. The classic version: a ground ball to the shortstop, who throws to second for one out; the second baseman relays to first for the other. Two outs on a single swing. Sometimes called a “twin killing” if you're feeling fancy.
Kills offensive momentum on contact. Bases loaded, no outs, ground ball — an inning can end before you reach for the chips.
Stolen base
A runner advances to the next base while the pitcher is delivering — no hit required. Pure speed, timing, and nerve. The catcher tries to throw them out; if the throw beats them, they're “caught stealing” and the inning loses a base runner instead of gaining one.
A steal of second base puts a runner in scoring position for free. Watch the runner lean off the bag on the next pitch.
ERA (earned run average)
The average number of earned runs a pitcher gives up per nine innings. Lower is better. Under 3.00 is excellent. Under 2.00 is historically great. Over 5.00 means somebody's losing their rotation spot.
If you remember just one pitcher stat, it's this one. It's the number that decides Cy Young awards.
Pinch hitter
A batter sent in to replace the scheduled hitter, usually in a high-leverage spot. Once they bat, the original player can't return. Managers use them to get a better matchup against the pitcher — typically a lefty hitter against a righty pitcher or vice versa.
Look for them in the 7th or later with the game on the line. A manager pulling out a pinch hitter is a real moment.
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