he developed his mass without losing his speed and explosiveness, if he would have only gotten bigger he would've waisted his time.
You have no idea how good in shape allistair is if you think his size is the only one that happent there... his everything happent, everything is bigger with him now, not just raw strength.
This is what I'm saying though -- he's obviously in very good physical shape, and you can tell just by looking at him. I don't mean to imply his muscle mass is responsible for his success; i'm just using it as the most obvious sign of his overall superior physical condition. His opponents all look like either smaller, weaker versions of him with no discernible difference in speed, endurance, power, or any other trait as far as I can tell (like I said though, I'm no expert), or like flat out dough mongers who, if they shed the pounds, would look like a smaller, weaker version of alistair.
How you look doesn't mean jack shit when the bell rings. Overeem has lost every single big fight against legit competition he has ever had in his entire fighting career (MMA wise).
Brock Lesnar is another example of how being a musclebound bufoon doesn't mean anything.
Overeem is a good fighter, but he is by no means a great fighter and he has been owned by what most on this site would consider smaller, fatter, unaesthetically pleasing fighters.
I understand that fighting skill counts for a lot, but I believe most of these fighters should still take their steroid use and weight training more seriously. Why would you want to come into a fight against an opponent who is bigger, faster, stronger, more powerful, and able to take more damage, fighting prowess aside?

? Even if he has lost to these "smaller, fatter, unaesthetically pleasing fighters," I'm sure he would have lost EVEN WORSE had they been in as good of shape as him. It just doesn't make sense to me.
I don't know much about brock, but what I do know is that most people criticize his fighting skill, and fear his mass, speed, power, and fighting spirit. He was a world champion, and maybe he wouldn't have been had his competition been in the same shape he had, instead of looking like tiny children in his presence?
And for all these guys who come into fights fat, WTF? How is that beneficial in any way?