To make it simple without doing all the research (I'm sure Tec will do it, he has lots of spare time apparently).
If the collective sum of all players on AAA was at, say for example, an OVR of 73 in season 18 and I kept them there so they would hit the big leagues in season 19 at a collective OVR of 75 (their season 18 progression), then starting all of their clocks a year later at a higher ability behooves me to do so. Most of them were done progressing after season 18, so keeping them an additional year in AAA would have made little difference. But I chose to keep them there in season 18 so they could collectively get better, which they did, and they did so without chewing up a year ML service time. Whether or not they were better than the current ML players is irrelevant. And doing this was not tanking.
With this last post, I am signing off on this topic. Ya'll can have the last word on this, it bores me. I'm not Trollish enough I guess.