Right now, maybe half of the top 15 (or so) interior defensive lineman are 6'1 or less and about 300 lbs or less and arm lenght of around 32 inches (Donald, Atkins, Casey, Daniels, Jarrett/Kyle Williams). Only Donald was a day one 1 pick or drafted in the first two rounds. Casey went in the 3rd round. No one else was picked in the top 100. I don't think there is an other position were so many top players share similar trait and most of them were picked late in the draft.
Are teams that afraid of having a small team that they automatically give worse grade for smaller defensive lineman? If Aaron Donald, for example, had Geno Atkins besides him instead of Michael Brockers, would that line be as effective as one would expect just from the player talent level upgrade from Brockers to Atkins or even worse? I mean, Brockers is a good player but Atkins is on another level. And individually these players are great but would they work as well together on the same line? Not sure if it's as much about the size itself as these players can use it to their advantage in quickness and leverage but maybe two dlineman with short arms would create some issues?
Just wondering why so many of them have fallen late in the draft. I understand that some teams want bigger, physical players (like BB, Parcells etc) but what about those teams that had already gotten steals later in the draft with small interior lineman would jump at the chance to select a player who had great tape and showed similar traits as their best defensive player. Like Grady Jarrett in 2015. Both the Bengals and Titans drafted a dlinemen in the 4th, Jarrett went with first pick in the 5th round Bengals pick was actually two picks before Jarrett was taken.
Though the Bengals did take Billings last year and he might be next to Atkins but he was another 4th round pick. And Titans did draft Mike Martin to be their nose tackle a year after taking Casey but he didn't pan out. And I maybe haven't looked at closely enough at bust/success rate for smaller defensive lineman so these guys could be sort of outliers and teams just missed on these guys for other reasons.