Fighters Missing Weight: Win Percentage?

On the topic of Darren Till coming in overweight again, I’ve seen more than a few instances of people citing statistics where fighters won at an astoundingly high rate in bouts where they missed weight.

Acquiring good data on MMA is hard enough, so we don’t have specifics on the intended divisional limit for all bouts.  However, we do have a ton of bouts with weigh-in data for both fighters.

I first retrieved a count of all pro MMA bouts that ended in a win, where we have actual weigh-in data that shows that both fighters were between 100 and 212 pounds (26,383).  The idea here is to exclude instances of bad data and Heavyweights.

Of these, I then looked at bouts where one fighter weighed between 1.75 and 6 pounds more than the other fighter.  This range seems arbitrary, but I was trying to avoid “freak show” type of matches, while also excluding cases where one fighter may be 169.5 and another at 171 (for example).  I got a surprisingly high count — 5,719.

Of these 5,719 bouts, the heavier fighter won 3,120 – 54.55%

When I change that window to a range of 1.25 pounds to 5 pounds, the win rate changes to 55.14%.