Sherdog.com’s 2015 Breakthrough Fighter of the Year

1. Holly Holm

Nothing spells “breakthrough” quite like a historic head kick, and the shockwaves Holly Holm’s shin sent through the sport are still being felt.

Holm made her Ultimate Fighting Championship debut on Feb. 28 and nine months later was seated on the women’s bantamweight throne. It was a whirlwind ride for the multiple-time boxing champion who transitioned to MMA in 2011 and won her first nine bouts before arriving in the UFC 193 main event opposite Ronda Rousey as the No. 1 contender at 135 pounds.

Few gave Holm a chance to unseat the seemingly invincible Rousey -- the Olympic judoka had beaten he three previous opponents in 64 seconds combined -- at Etihad Stadium in Melbourne,…