Fair enough, but I actually think that's more perception than reality in my mind. Keeping in mind that you have to be at least 2-deep at both the RB and TE positions to protect from injuries in a season you're hoping to compete for a while... Which 2 TEs and 2 RBs have provided you a high degree of confidence that they're going to be Championship caliber players?
I think that it's reasonable to suggest 1 of Flanagan, Flanigan or Premer will emerge as a 1A or 1B Championship caliber TE, but I think it's a stretch to assume that two players will emerge there in the same year and play at that level. For that reason I'd rather add a proven guy if I can get somebody like Foley, and develop the second guy internally.
Same argument at RB. I think it's safe to assume that 1 of Aneyas Williams, Kedron Young or the freshman will be ready to be a Championship caliber 1A or 1B running back, but I think it's bold to assume that 2 players of that caliber will emerge in the same cycle. Therefore, if you can can get a proven rusher in the Portal to pair with whichever guy emerges from your deoth chart, you do that. Especially given ND's interest in a two back system.
Let's apply that same logic to the defensive tackle group. You need 4 players you're confident can rotate between 2 positions and play at a high level. You have one of those players in Elijah Hughes, who played meaningful snaps last year. That leaves Mukam, Mullins, Sevillano, Dixon, Burgess and Golden and some projects. If you're not confident that at least one of those guys can emerge as one of your top 4 DT/NGs, you need to scrap your entire recruiting operation and start over, because it's failed you. So for argument sake, let's say you have Hughes + whoever emerges from that group. That leaves you 2 spots left in your top 4 for a combination of Onye and / or 2 Transfer Portal Additions. Personally, unless you can get an underrated 3rd guy for super cheap for super cheap, I think 3 players is overkill and a misuse of Portal funds.