I've talked about this a ton in some of the small receiver threads.
I used to really covet the 6'3 220 build. If you weren't that, you were knocked down a point for each inch below that. 5'10 is laughable. 5'8? Get out of here.
The NFL has changed. These smaller dudes can succeed now. "Small" isn't a death sentence for their fantasy value.
Keep in mind when looking for comps--you've got to go to the Combine to get their real height. Tyreke Hill is listed as 5'10 on every website: Wikipedia, ESPN, Yahoo, Rotoworld, NFL.Com, etc. If you dig his combine measurments back up--he was 5'8.
Jaylen Waddle was 5'9 and change.
Devonta Smith's weight/BMI was supposed to keep him from having a fantasy impact.
Now, you're gonna say "Those dudes are elite talents though." Sure they are. And a lot of 5'8/5'9 guys are going to fail. That said, a lot of 6'2 and 6'3 guys don't pan out, either.
I think the take away is: You don't eliminate a guy for his size. If the rest of his game is going to put him in a position to have fantasy success--don't write him off simply due to being too short or too skinny.
Now I'm not telling you that I never have pause over a guy's size. But it's calmed down a lot compared to 3-4 years ago. There's probably a limit. Tutu Atwell at 155 Lbs still makes me think we're probably too far out from under the bell curve.