It's widely acknowledged that running back is among the positions where rookies can come in and show the natural quickness and vision that will project their course in the NFL.
To compare Morgan Moses and Samaje Perine to me is a bit absurd. Perine is not particularly quick, doesn't have great vision and doesn't break tackles. As a running back exactly what are his strengths?
That's an oft-repeated belief that isn't really supported by the facts.
Here are 5 years worth of top 5 RBs (per NFL com - apparently some combination of total yards, yards/attempt, and other stats). For simplicity's sake, I'm just going to list the total rushing yards.
2013
Lacy 1178
Stacy 973
Bell 860
Ellington 652
Bernard 695
2014
Hill 1124
Mason 765
McKinnon 538
West 673
Williams 721
2015
Gurley 1106
Rawls 830
Yeldon 740
Williams 517
Gordon 641
2016
Elliott 1631
Howard 1313
Kelley 704
Booker 612
Washington 467
2017
Hunt 1327
Fourette 1040
Kamara 728
Mixon 626
Perine 603
With a few exceptions, what those stats tell me is that it is very rare to see a rookie RB with dazzling stats right out of the gate (and we are looking at just the top performers during those 5 years). For every Ezekial Elliott, there are 10 other rookie RBs with less than 500 yards total. It's worth noting that Kelley and Perine were in the top groups in their rookie years, warts and all, and that is despite the fact that the Redskins are hardly a rush-heavy offense, and that both played in a running back by committee system. Had either been the 'featured back' consistently they'd easily have exceeded 1000 yds, maybe more in their rookie years.
If you look at probably the fairest measure, yds/attempt, in 2016 Rob Kelley ranked tied for 18th in the league with a 4.2 yard average. That's not great - but that's all RBs and he was a rook splitting time with Matt Jones. In 2017, Perine was much less impressive, tied for 43rd place with just a 3.4 yd average, but again playing in a RB by committee system.
I'm not arguing either will be a perennial pro bowler. But they both have the potential to be solid NFL running backs (particularly Kelley, pre-season performance aside). The idea that we should know immediately based on rookie performances what a RBs potential is may be true. If so - maybe we're in better shape given both Kelley and Perine's rookie years and how they compare to other teams RBs.
I respect that I have the minority opinion and that time will tell if either of these guys has the talent to be a starter. My main argument is that both have just 1 full season of work, and that the results of their full rookie years should give us hope, not lead us to give up on them.