There were several other big guys along the way, and I won't include the pure fullbacks (Zellars, Edwards, Spencer, Powers-Neal, etc:)
Just off the top of my head:
Tony Fisher - 220 lbs, horribly underused.
Robert Hughes - 230 lbs, again not used enough
Jonas Gray - 220 lbs
Cierre Wood - 215 lbs
Josh Adams - 230 lbs
Tony Jones Jr - 230+ lbs
But yeah, I do agree, that Brian Kelly seems to be shooting more for the smaller, shifty backs, instead of trying to go for the power runners.
I'm quite happy with the one-two running back tandem we have for next year (Kyren Williams + Chris Tyree), and feel excited to see what Estime and hopefully Diggs, can do. I think that with another year of S&C under Coach Balis, you'll see Williams and Tyree add about 10 quality pounds to their frames, which will make them even better in 2021.
I'll be realistic here though... Trying to say that C'bo Flemister is a power back is a bit of a reach. He's more of a small back who runs straight ahead with some good hard momentum, instead of a big guy who can bulldoze you.