I am hoping that the interest in not using all 13 spots was limited to not wanting to recruit even more transfers from the portal as one and dones. I seem to recall that he also talked about balancing classes so hope that this played some part in his decision last year.That pretty much matches my order of preference. First of all, I hope he does recruit 4 transfers instead of 3. He should abandon his reluctance (as he stated last summer), at least temporarily, to fill all 13 spots with scholarship players. He said something like "you can't keep 13 players happy" but no coach ever lost his job or the support of the fanbase because he didn't keep all 13 players happy.
I could be wrong but I suspect Johnson will want to give the substantial majority of front court minutes to Ihnen and Fox because they are short-timers, he owes them to some degree, and they each lost a year due to unfortunate injuries. Because of that, it may make more sense to recruit a younger transfer big man who showed some potential in his first year but is willing to come off the bench until he's an upperclassman.
I also hope that seeing the impact of no bench and injuries on the team this year will illustrate the need to have a few more warm bodies available.