Another "if we land Lattimore" question...does it guarantee anything? Well, of course not, you just never know who will turn out to be what.
However, looking back to 2002, here are all twenty 5-star running backs. If you're a college football fan, you'll recognize nearly every name.
Ciatrick Fason
Gerald Riggs Jr
Jarious Norwood
Reggie Bush
Kregg Lumpkin
Demetrius Summers
Adrian Peterson
Jonathan Stewart
Marlon Lucky
Jason Gwaltney
Kevin Grady
Chris "Beanie" Wells
Stafon Johnson
Marc Tyler
Joe McNight
Jermie Calhoun
Darrell Scott
Christine Michael
Trent Richardson
Bryce Brown
A few had injuries that slowed them (Marc Tyler, Kregg Lumpkin, Kevin Grady), a couple were trouble guys and got kicked off their teams (Demetrius Summers, Jason Gwaltney), the USC guys shared time with 27 other 5-star running backs, and Darrell Scott was kind of a dud.
But aside from injuries and troubled kids, most of these guys contributed to their teams to varying degrees...anywhere from being among the leading rushers in their conference (Marlon Lucky, Gerald Riggs Jr, Joe McNight, Jerious Norwood, Ciatrick Fason) to being among the best in the country (Adrian Peterson, Reggie Bush, Beanie Wells, Jonathan Stewart). Then there are a few that seem destined to be notable as well (and already are to some extent), such as Brown, Richardson, Michael, and Calhoun.
If you subtract the injured and wayward, then both Dyer and Lattimore each has about an 87% chance of being a significant contributor to Auburn. Each guy also has about a 26% chance of being among the best in the country.
If we factor in the injured players (because that can happen to anyone), they each have a 72% chance of being significant contributors (among the league leaders), and a 22% chance of being among the nation's elite.
Of course, a sample size of only 20 guys isn't much, so who knows, one could be a dud and the other could have nagging injuries their whole career...it happens. But I would say that of the 20 guys named 5-star running backs the last 8 years, the group as a whole have had a pretty darn good showing.
In fact, subtracting the injured and wayward again, every guy on this list that isn't still in school has spent at least some time on an NFL roster.