Has Rahman had a prime?

Most fighters have a stretch of fights where you can look at and say "this was so and so's prime" but does Rock have a period where you can reflect on and say, here it is? Chris Byrd is a bitch but he definately had a period where he was at his absolute best...if I had to pinpoint a time when Rock was at his best it was before he ko'd Lewis (actually when he got ko'd after the bell by Tua). Are there any other examples of fighters who appear to be prime less? Is Rock still trying to find himself or is it too late or has it already come and gone or is he the man that landed 1 right hand and the rest of his career shit all over himself?