Which modern fighters had the quickest sudden fall from their prime?

Roy Jones seems to be the poster boy for this. Although I certainly dont think he was in his prime when he lost to Tarver (I think his peak was probably '94 - 98), he was still viewed as pretty much unbeatable at the time. But he was never same after, and declined very rapidly IMO. He looked absolutely shot to bits in the Glen Johnson fight and should've retired then.

 

Kambosos Jr. Beat Teo pretty handily then got schooled by Haney and became a gatekeeper.

 

Usyk been at the top his whole career?

 

For added context: Kambosos was in his physical prime at the time he beat Lopez, and he then lost his next 4 fights in a row - yes, the Hughes fight was a massive robbery. Kambosos then beat a local kid, and in his next fight got beaten down by Hitchins.
Kambosos was 32 at the time of the Hitchins fight.

In his physical prime, at the championships level, Kambosos went 2-4. I cant imagine him being able to turn this around now.

 

Usyk looked great against Dubois 2, then looked human and mediocre against Rico.

 

Usyk was 39 tho. Cant really claim someone is in their prime at that age, and his physical decline is very noticeable from the WBSS to Joshua, to Dubois 2.

 

Joshua