MLB
What Is OPS in Baseball? OBP Plus SLG Explained with Real Math
OPS adds on-base percentage to slugging percentage. Learn both formulas, follow a full worked example step by step, see how OPS+ adjusts for league and park, and what counts as good.
MLB Rules and Stats Explained
The rules that confuse new fans and the stats that decide arguments, from the infield fly rule to OPS and ERA with worked examples.
6 articlesMLB
What Is ERA in Baseball? Formula, Examples and Earned Runs
ERA is earned runs x 9 divided by innings pitched. See worked examples with partial innings like 6.1, how earned and unearned runs differ, and what ERA+ and FIP add.
MLB
What Is a Balk in Baseball? The Rule, Penalty and Examples
A balk is an illegal pitcher motion with runners on base, and every runner moves up a base. Here are the main ways to balk, the penalty and its exception, and clear examples.
MLB
The Infield Fly Rule Explained: Conditions, Examples and Myths
The infield fly rule makes the batter out on an easy pop-up with runners on first and second and fewer than two outs. Here is when it applies, why it exists, and what runners can do.
MLB
How Many Innings in Baseball? MLB, Extra Innings and Rain Rules
An MLB game is nine innings, but it can end after eight and a half, run into extra innings with an automatic runner, or be cut short by rain. Here is how innings work at every level.
MLB
How Long Is a Baseball Game? MLB Average Times and the Pitch Clock
The average MLB game took 2:42 in 2026, down from more than three hours before the pitch clock. See times by season, what slows games down, and doubleheader and playoff lengths.
Baseball has the longest rulebook of the major US sports and the richest set of statistics. This section picks out the rules that confuse new fans and the numbers that settle arguments, and explains each one with examples. Rules are checked against the current Official Baseball Rules.
Innings and game length
A regular game is nine innings, but it can end after eight and a half, go to extra innings with an automatic runner on second, or be shortened by rain. How many innings in baseball covers every case. Games have also become much shorter since the pitch clock arrived: how long a baseball game lasts has the average times by season.
Rules that puzzle new fans
The infield fly rule makes the batter out on an easy pop-up with runners on first and second and fewer than two outs, so the defense cannot drop the ball on purpose for a double play. What is a balk explains the illegal pitcher motions that move every runner up a base, including the limit on pickoff attempts.
Stats explained
OPS adds on-base percentage to slugging percentage to measure a hitter in one number. ERA measures a pitcher: earned runs multiplied by nine, divided by innings pitched. Both guides include worked examples with real arithmetic, plus the adjusted versions, OPS+ and ERA+.