I think an underappreciated part of the 72 win season was that there were two expansion teams that year. That drops the strength of schedule by a bit. It probably only increased the total wins by 1 or 2, but that is enough when shooting for a record.
One of The Bulls loses actually came against the 21-61 Toronto Raptors, and it wasn’t even on a back to back.
The point about expansion isn't the two most recent teams that year. It's that the NBA had added 6 new teams in 7 years with that season. That's a lot of 1st round draft picks going to crappy teams instead of Bulls' competitors.
I think that's a valid point.
Although I wonder on the flip side of that, is it easier to play 14 teams in your
conference 3-4 times a year, or the 10-11 teams in your
conference 5-6 times a year (in the 80's). Or we can take it back even further, and play every team in the
league 4-8 times a year (in the 70's), or every team in the
league 10 times a year (in the 60's).
Plus I wonder if it's tougher traveling to 22 different cities, as opposed to 28-29 different cities, or just 10 different cities. You're still playing 41 games on the road, but more cities might make the travel more "grueling."
Not that I disagree with the expansion theory, just something to think about on the flip side of it.