Alistair has certainly improved, I love watching him fight and consider myself a big Reem fan, but I don't see this monumental improvement that many seem to. As far as I can see, he's pretty much the same fighter, that has improved his stand-up, and improved his strength and conditioning routine. I think people have been fooled by the muscle gain, and run of victories over average competition (bar Lesnar) into thinking Alistair is some unbeatable monster, which just isn't the case. Alistair's chin still has question marks surrounding it, and he has a history of quitting when fights aren't going his way. Look at his fights with Chuck Liddell, Sergei Kharitonov, Shogun Rua, and Ricardo Arona went. He took shots from top level guys, and buckled.
He might have a more diverse range of strikes than JDS, but that means very little when the guy standing in front of you has the ability to eat up those strikes, and blast you with the very high level single striking dimension he possesses. Dos Santos has blasted excellent strikers in Cro Cop and Yvel, put flawless beatings on Carwin and Nelson, brutally knocked out Velasquez, Werdum, Struve and Gonzaga and made Cro Cop quit. JDS is the real deal, and I think we're going to see just how good his striking is when he puts a beating on Overeem. Alistair's leg kicks have never been his main weapons, he mainly uses his knees, and his punches. I don't see him being quick enough to out-land JDS in the punches, nor get inside quickly enough to gain the clinch, and blast JDS with the uberknees; and even if he does, I can see JDS taking them, and continuing to move forward. Dos Santos can take a shot! Also, I see cardio definitely playing a part. Alistair does not have the same cardio as JDS. He slowed down hugely in round 3 of a fairly slow fight against Werdum. JDS blasted Nelson for 3 rounds without slowing down at all, and he only slightly slowed against Carwin after putting everything into trying to finish early in the fight. In the cardio department, Alistair's size does not play in his favour, he's slower than JDS to begin with, so if he cannot maintain his conditioning after Round 2, if the fight is still going then, we could really see JDS putting some punishment on him, Alistair will slow.
As for the K-1 comment; don't get me wrong, it's a massive achievement for an MMA fighter to transition to K-1 and take the GP, but it was probably the least impressive K-1 field in history. The 2 best guys in that GP fought eachother in the quarter finals, Gokhan Saki and Daniel Ghita, and that hugely assisted Alistair in getting to the final. Gokhan was badly injured after the Ghita fight, only having use of 1 arm, yet he was still beating Alistair up. If Gokhan Saki was healthy going into that fight, he'd have beaten Alistair, I don't think there's any doubt about that. Then in the final he gets drawn against a worn out 40 year old Peter Aerts who'd just had a war with Semmy Schilt, it's not like he took out Hari, Hug and Hoost. Sure, he beat the guys put in front of him, but I'm not sure it's as impressive a feat as people are making out. Still an impressive achievement don't get me wrong, and he is one of the elite strikers in all of MMA (certainly in my Top 3) but not quite as impressive as a lot are making out.
I don't want this to appear like I'm hating on Alistair, I'm not, I just think people need to be a little more realistic. Alistair is not unbeatable, he does have flaws. He might be built like a greek god, and be on a run of decisive victories, but there are ways to beat him, and I just think JDS has the skills to take him out. It's going to be an awesome fight no matter what the outcome though, this is the best HW MMA Fight of all-time, I can't wait for it!
be on for it's first UFC title ever, JDS has got to figure out a way now to fight Overeem because standing with him, isn't his best bet and if he does Overeem should have his number. 
