What is a Pop-Up Rate? Definition, Formula, and Example
Pop-Up Rate (PO%) is the percentage of a batter's batted balls that are hit weakly into the infield with a launch angle between 10 and 40 degrees, resulting in an easy out.
What is Pop-Up Rate (PO%)?
Pop-Up Rate (PO%) is the percentage of a batter's batted balls that are hit into the infield with a launch angle between 10 and 40 degrees and an exit velocity too low to carry into the outfield. In Statcast terminology, a "pop-up" (often categorized as a weak fly ball) is the least desirable outcome for a hitter outside of a strikeout. These balls are caught virtually 100% of the time by infielders. Pop-Up Rate measures how often a hitter falls victim to this weak contact, serving as a key indicator of swing mechanics, timing, and barrel control.
How Pop-Up Rate is Calculated
The formula for Pop-Up Rate is straightforward:
Pop-Up Rate = (Pop-Ups / Total Batted Balls) × 100
Statcast and various sabermetric platforms define a pop-up by combining specific batted-ball metrics. The criteria generally require a launch angle between 10° and 40° combined with a low exit velocity (typically under 90 mph) and a short hang time. Because these balls do not travel past the infield dirt, they possess a near-zero chance of becoming a hit. To calculate it manually, you divide a player's total number of pop-ups by their total number of balls in play (excluding home runs and bunts) and multiply by 100 to get a percentage.
Worked Example
During the 2023 MLB season, Oakland Athletics utility man Esteury Ruiz struggled with elevating the ball with authority. Of his 350 total batted balls, a significant portion resulted in weak infield air outs. If Ruiz hit 42 balls that met the pop-up criteria (infield fly, 10°–40° launch angle, sub-90 mph exit velocity), his Pop-Up Rate would be calculated as:
(42 / 350) × 100 = 12.0%
A 12.0% Pop-Up Rate is significantly higher than the MLB average (which hovers around 3.5% to 4.5%). By contrast, a elite line-drive hitter like Freddie Freeman maintains a Pop-Up Rate consistently below 3.0%, ensuring his balls in play actually challenge the outfielders rather than gifting easy outs to the infield.
Why It Matters
Pop-Up Rate is a critical metric for front-office analysts and fantasy baseball players because it acts as a drag on a player's Batting Average on Balls in Play (BABIP). While a high Ground Ball Rate can suppress power, a high Pop-Up Rate suppresses both power and batting average simultaneously. When evaluating a minor league prospect or a slumping major leaguer, a sudden spike in Pop-Up Rate indicates a mechanical flaw—often a failure to stay behind the ball or an uppercut swing path that is getting underneath the baseball. In DFS and daily fantasy, identifying hitters with surging Pop-Up Rates allows players to fade struggling offenses against elite strikeout pitchers.
Limitations and Common Misconceptions
A common misconception is that all air balls are created equal, leading people to confuse Pop-Up Rate with standard Fly Ball Rate. Standard fly balls travel to the outfield and have a legitimate chance of dropping for hits or clearing the fence for home runs. Pop-ups are exclusively infield air balls with zero run-producing value. Another limitation of the metric is that it does not differentiate between a pop-up to the pitcher and a pop-up to the shortstop—both are statistical zeros, but the underlying spray chart data can sometimes reveal whether a hitter is completely fooled or just missing his ideal launch angle by a few degrees.
Related Terms
In Legends Deck
In Legends Deck, Pop-Up Rate directly nerfs a card's "Contact" and "BABIP" attributes. High Pop-Up Rate hitters see their in-game simulation heavily weighted toward easy infield outs when facing pitchers with high Vertical Break or elite Extension, preventing them from stringing together rallies. When evaluating a card's true value, always check their Pop-Up Rate—low percentages translate to harder-hit balls and more consistent on-base results in your simulated matchups.