You know, maybe this whole "UFC in Los Angeles" thing isn't meant to be. UFC 176 got cancelled last year, and UFC 184 has lost a lot of its luster due to injuries. Chris Weidman is injured and his main event with Vitor Belfort was scrapped, but the UFC is still trying to get him a spot on the card. Ronaldo Souza contracted pneumonia and is out of his main card fight with Yoel Romero, and Antonio Silva versus Frank Mir was moved to Brazil because that card's main event of Rashad Evans and Glover Teixeira was called off.
As a result, Ronda Rousey and Cat Zingano move up to main event, while Holly Holm and Raquel Pennington go from main card opener to co-main event. Who knows what will happen in the next few weeks as far as keeping Belfort on the card? Maybe Ben Henderson will move up to 185 after he's done with Brandon Thatch on February 14th.
Anyway, here's your current bout lineup for UFC 184 on February 28th at the Staples Center in LA: