plus a thousand or ten thousand other variables
there are not simple takeaways
We are splitting this hair right down to the smallest bit, and I'm honestly unsure if we're all not sort of on the same page, but pushing around little elements of minutiae.
There are system factors.
There are defensive focus factors.
There are talent factors.
There are surrounding talent factors.
There are fatigue factors, the runner in question's first and foremost, but the opponent's as well.
I'm sure I'm missing some.
I think we can say that, chances are on average, more carries make someone more tired, and tired people are, on average, worse at breaking long runs. This is not all the time. There are some freaks. There are some runners that get lathered up. There are some systems that funnel carries or certain ways or set up certain situations. (There's also a question of the outlier nature of long runs and efficiency, which would totally be fun to break down in a different sort of in the weeds discussion).
My small view. More carries often make it harder to keep a high YPC because of fatigue and situational factors. But not always, owing to talent differences and systems and other oddities.
Vote Melvin.
(I always like to look at the YPC stuff for modern triple teams because it's interesting to see how they fit or don't fit the patterns/roles. It's a little harder with old Nebraska because that FB role, and sometimes QB role is less well defined)