MLB Ball Carry Tracker

MLB ball flight and drag tracking

Measured drag on batted balls and how far they actually carry, tracked over the season. The purpose is to separate two explanations for a change in league offence that look identical in a box score: a change in the baseball itself, or a change in the conditions it is being hit in.

How drag changes home run totals

Drag is the air resistance acting on a ball in flight, and small changes to it move fly ball distance more than most people expect. A shift of a few feet of carry is not noticeable on any individual swing, but it converts a meaningful number of warning-track outs into home runs across a whole league.

That is why league offence can move sharply without any change in how players are hitting. Exit velocity and launch angle can be flat year over year while home run totals jump, and when that happens the explanation lives in the flight of the ball rather than in the swing.

The confounder is weather. Warm air is less dense and balls carry further in it, so a hot stretch produces exactly the same signature as a livelier ball. Distinguishing them requires holding temperature and altitude constant and asking whether the ball still carries further than it used to.

Why this matters for projections

Home run projections are built on past rates, so if the ball changes mid-season every one of those rates is describing a slightly different game than the one being played. Power projections are the first thing to drift when carry changes and the last thing anyone thinks to check.

It also affects totals. A league-wide carry change moves run environment for every park at once, which is the kind of shift that gets attributed to pitching or to hitters heating up long before anyone looks at the ball.

Frequently asked questions