I've been asked by a few people about my thoughts on the Rousey/Holm fight. Many people have mentioned that Holm had much better footwork, but it's more specific than that. When an orthodox fighter matches up with a Southpaw (the right-handed Rousey against the left-handed Holm) the fighter with the lead leg on the outside of the other is in a better position to throw the power hand (Holm's left vs Rousey's right) down the middle and through the opponent's guard. That's a basic facet of boxing, and something Holm is very well aware of. Holm was using a lot of lateral movement, and when her right leg was outside of Rousey's left leg, she'd shoot the left hand lead down the center and through Rousey's guard, cracking her numerous times. With Rousey's lead leg on the inside much of the time, a lot of the effectiveness of her right hand is taken away, even if she was able to throw it much. She wasn't, because Holm wasn't about to stand still to let her do it. She'd throw the left hand, and then jab her way out of distance so Rousey couldn't counter.
Holm's never been a big puncher, but she planted her feet and sat down more on her punches than she usually does, and Rousey was amplifying Holm's punching power by stepping forward into the shots that Holm was throwing. Rousey's shown a good chin in the past, but that's never advisable. This was amplified by the fact that Ronda wasn't moving her head off the center line, meaning her head was stationary as she came forward, giving Holm a much easier target to hit. She tends to keep her chin up when throwing shots as well, which is a dangerous habit to get into. A tucked chin helps protect against a knockout shot. Holm also uses her punches to set up the head kick, so Ronda needed to keep her hands high to protect against that. The kick that knocked her out in the second round was from behind (I think she was badly dazed already), so she never saw it coming, and those are the shots that do the most damage because your nervous system has no time to prepare for the impact.
It's been said a lot, but is absolutely true: Ronda chasing Holm around the cage was a dangerous strategy, especially with the aforementioned footwork and lateral movement advantages that Holm had. After the first round, my thought was Ronda needed a lot more head movement. She needed to plant her feet as soon as Holm started moving away and wait for her. That's not how Ronda usually fights, but it would have made Holm have to change tactics. Stop, and make Holm come forward to her. When Holm comes forward, work leg kicks on the lead leg to nullify Holm's reach advantage (Rousey can reach Holm with a kick from a further distance away than she can a punch) and to take way Holm's speed and lateral movement over time. This gives Holm something else to worry about defending while also slowing her down, so Rousey could initiate the grappling exchanges that are to her greatest advantage. This would also conserve Ronda's energy, since she looked exhausted after round 1, and ideally wear down Holm because grappling for extended periods can suck the life out of fighters who haven't done it for as long as Rousey has.
End of the day, both are great champions who are great for the sport and for women advancing in it. If a rematch happens, it'll be a huge event that could break all sorts of records. Rousey's earned an extended break after the grind she's been on, and Holm has earned her place in the spotlight. Rousey has nothing to be ashamed of, but needs to make some major changes prior to a return, while Holm has finally realized the greatness that many were predicting for her when she first transitioned into MMA. Congrats to both of them, and I hope Ronda heals up quickly and can enjoy her life until such time when she decides to come back. (UFC 200?)
Oh, and this really isn't the biggest upset in UFC history, despite what ESPN says (not sure about betting odds, but as far as conventional wisdom before a fight...) Georges St. Pierre's knockout loss to Matt Serra for the Welterweight title likely still has that distinction.
My two, three or four cents. :-)