Below is a list of champions from the two preeminent MMA organizations at the time, five years ago.  My memory's less than stellar so I utilized Wikipedia to source the information.  If I screwed up, let me know.  I left out lightweight because the UFC title was out of circulation for a good while.  Coincidentally, not long after February of 2006, both Hughes and Franklin yielded their titles to the two top pound-for-pound guys (at least in my mind) in the sport - Georges St. Pierre and Anderson Silva.

UFC Champions (February 2006): 

Heavyweight - Andrei Arlovski

Light Heavyweight - Chuck Liddell

Middleweight - Rich Franklin

Welterweight - Matt Hughes

Pride Champions (February 2006):

Heavyweight - Fedor Emelianenko

Light Heavyweight - Wanderlei Silva

Welterweight - Dan Henderson

Quite obviously, the goal of this exercise is to illustrate how things change in just a few short years.  I won't break down all the careers of all the fighters on the list.  Sports fans have long witnessed to the athletic deterioration of once elite competitors in various sports.  MMA is no different.  In fact, in some respects the fall is often times much steeper.

Fedor and Arlovski may or may not be finished after last night's Strikeforce heavyweight tournament matches.  These once almost unstoppable fighters looked very much the mortals they truly are.  That's sort of the fascination with high-level athletes.  They accomplish things that seem almost impossible.  Whatever the personal nemesis, whether it's all physical, all mental, or a combination of the two, most world-class athletes don't exit on top.

Clearly, some will argue - especially in the case of Fedor - that the athlete in question can make some changes and return to greatness.  Perhaps, that's the case.  However, the above list, while only a snapshot, starkly depicts the cruel reality that is the constant advancement of time.