I just checked 11 Jul 2017 ATL-GNV (and several others listed below).

7 flights that day, one a 717, the rest appear to be 50 seaters with the following caveat:
"Operated by Connection Carrier, EXPRESSJET DBA DEL"

Also saw ATL-HPN, all expressjet; ATL-BHM, ATL-TRI, ATL-XNA, ATL-YUL, ATL-YYZ, ATL-VLD, ATL-VPS, ATL-HOU and on, and on... most if not all operated by expressjet.

I did see a sprinkling of endeavor in some of the city pairs in there, but not what I expected based on your post.