I seem to remember an interview done by Doug Flutie saying one of the adjustments he had to make coming up to Canada was the bigger ball. That was in the 90s, so maybe in the early 90s they were still using the fatter ball.
From what I remember, they only changed to the smaller sized balls during US expansion (so around mid-90s-ish).
Don’t know if that was ever a good thing, it means we didn’t get laid enough.