The man is my favorite fighter. He got me into MMA, the first fight I ever watched was when he decapitated Thiago Silva.
That being said I think Lyoto at some point stopped evolving, and after he was figured out, the game passed him by.
This seems to happen to strikers quite a bit, think Cro Cop, Anthony Pettis, Anderson Silva, and Carlos Condit.
Strikers rely more on youth for the reflexes, power, and speed advantages, while grapplers can continue to have success past their prime due to their ability to take the fight wherever they need it(in MMA). This isnt a rule across combat sports. A wiser, craftier veteran boxer can still take out the young elite in a purely striking art (see Bernard Hopkins), but in mma the older strikers cant cant rely on there vetwran tools to win fights (see Anderson Silva). Just think about how many more Wrestlers fight later in there 40's as oppose to strikers.