Rankings are still fluid, especially in the first tier, but here's how I roughly see those guys:
Samaje Perine - Always liked him, while at the same time recognizing his limitations. Bit sluggish and may only be a two down guy. Burst is very average. Is he too slow for the NFL? Maybe. Looks and runs like an NFL back though. Rudi Johnson is a comparison I've made in the past, and he was drafted in almost the exact same spot. High floor/low ceiling. Best value is in 2RB leagues. Value drops off a lot in leagues with only one mandatory RB spot, as he doesn't look to have a huge ceiling unless the situation is just perfect.
Alvin Kamara - Feel like he was overdrafted based on versatility, kind of like Drake and Prosise last year. Not sure he really has featured back skills. Never carried the load in college. Doesn't really jump off the screen for me, though he looks okay. Bit of a boom-or-bust pick IMO. Could end up being a better Latavius Murray or a more power-oriented version of Demarco Murray. Could be irrelevant in two years.
Kareem Hunt - Studied him a lot two years ago after his huge sophomore season. Looked like a poor man's Todd Gurley to me. Always kind of liked him, but never had total faith. Interesting one. Stronger than his listed weight would lead you to believe and has some speed despite slow 40 time. Cuts/footwork are not always super clean, but for a bigger guy he can move a little bit. I can see him thriving in the NFL, where big backs with some burst/moves usually do okay.
D'Onta Foreman - Not a lot of "wow" factor, but has power and some decent north-south ability. Some similarities to former Texas RB Cedric Benson and could be a similar pro player. Solid, no-nonsense power back. Should push Miller right away.
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Jamaal Williams - Has a little flash and plays above his measurables. Lively runner. Has a little bit of power and can cut well. There's something there, but is he really an NFL starter? We may find out next season if Montgomery/Michael can't get the job done.
Marlon Mack - Reminds me a bit of Wendell Smallwood from the 2016 class. Both guys have nice fluidity in their cuts and movement, but both lack the raw athletic parts (size/speed/explosion) to obviously be special pro backs. Probably a JAG in the NFL, but short-term opportunity is there.
Wayne Gallman - Similar to Mack for me. Scrappy runner with better game speed than 40 time, but I don't really see it happening for him in the NFL in the long run.
James Conner - Meh. Plodding big guy. Not explosive. Nice story, but I don't think he was worth a 3rd rounder for the Steelers.
Donnel Pumphrey - Irrelevant.
Joe Williams - Irrelevant.