Are Wins Against Past-Prime Big Opponents Really That Invaluable?

It's swings and roundabout s in a way. Some wins over past champs are seen as important or ness, such as Marciano v Louis or Holmes v Ali. It doesn't devalue either fighter really imo.
Another instance is Jack Johnson v Bob fitzimmons, We all know that Bob was well over the hill, that fight didn't really need to happen but I suppose it looked impressive on Jack's record.
Same as Louis beating Carnera, Baer and Sharkey, he didn't really have to face those guys I should imagine, he was looking hot, at least until he faced max Schmeling that is!
Then you have the past champs that become stepping stones, like pinklon Thomas, losing to Holyfield and Morrison. Tho sometimes that can come back on the upcoming guy like Louis and Schmeling and almost Bowe v Tubbs.

 

Fitzsimmons was in his middle 40's and washed up.
The difference is Carnera was ranked in the top 5 and was 29years old, Baer top 3 and 24 years old.
Sharkey was washed up too when Louis got him.
The nature of the sport is the young feed on the old.

 

It can be valuable to an up and coming prospect. That fighter will observe first hand, various different styles, he may later see in future opponents. It serves as a good teaching tool, for that fighter to gain experience. As the saying goes, Experience Is The Best Teacher, and it is something you cannot learn from a book. And lastly, a young fighter gains confidence.

 

All valid points.