Reaching Base on Error

I’ve done a ton of research over the years for Baseball Mogul and Football Mogul and I think it makes sense to try to share it so it doesn’t get lost to the sands of time.

Today’s post is about batters reaching base on an error. Most baseball simulations use the defense's stats to determine if a fielder commits an error — but ignore the fact that faster runners are more likely to reach base on an error than slower runners. Cal Ripken might bobble a hard ground ball to short. But if he keeps it in front of him, he probably still has time to throw out a runner like Cecil Fielder. Against a batter like Roberto Alomar, the same ground ball goes in the record books as a fielding error.

To estimate this effect, I created two groups using data from 1980-2022. “Fast Runners” were defined as the top 20% of players ranked by Bill James’ Speed Score. I designated the bottom 20% as “Slow Runners”:

Translated to Baseball Mogul, a player with a Speed Rating of 90 is about 50% more likely to reach base on an error than a player with a Speed Rating of 60.

There's also a difference by handedness. Lefties start a step closer to first base, but right-handed hitters are far more likely to hit a ground ball to the left side of the infield (SS and 3B) where most infield errors are recorded. Overall, righties reach base on a error about 20% more often than lefties (after adjusting for running speed). This advantage is fairly consistent across all seasons. The difference is smaller before 1940, probably because hitters were less likely to pull ground balls.

Two-Base Errors

About 18% of the time that a batter reaches base on error, it’s due to a throwing error. Some of those throws let the batter reach second base. These two-base errors are much more likely with fast runners than slow runners:

​This isn’t a surprise. We’ve all seen fast runners take the turn and head for second on an overthrow. But a sim that only uses fielding stats to decide when errors occur (and what type) will fail to reflect this nuance of the game.