Who was more past their prime: Dempsey in 1926 or Louis in 1946??

I'd say Dempsey. Louis still had enough left to beat Jersey Joe Walcott,twice,one and two years past 1946. He'd also kept himself in trim doing his army stint. Dempsey had been living the life of luxury for three years prior to his first fight with Gene Tunney.

 

Dempsey. Louis came out of the Army and picked up where he left off. Dempsey was shot after his 3 years in Hollywood. Id dare say that the comebacking Louis was better then the past prime Dempsey.

 

I think Louis had lost more but was always a better fighter so despite being further down the hill he was still able to compete at a higher level.

 

Probably Dempsey because he'd been very inactive every since he won the championship in 1919. He went downhill slowly but surely since then.
He went to Hollywood in 1919 or 1920. He took 2 years off 1921-'23. He was off another 3 years.
He fought some exhibitions, but not as many as Louis.
It was basically Louis's full-time job to fight exhibitions for most of his 4-year lay-off.

 

I'd say Louis. His steady slippage -- although he was still the best in the world in 1946 -- can be seen fight by fight through the latter years of his reign.

I don't think Dempsey was so much past his prime as he was rusty, and then he ran into a guy who would have probably given him fits and thoroughly outboxed him at any point in his career.

 

Louis looked quite devastating against Tami Mauriello in 1946.
And Mauriello was no mug, he was the #1 contender.