To answer the original question asked....

AZO, PIT and ERI have all had CO service from CLE in the past. PIT and AZO had RJ service, but I think ERI got cut when COEX dropped props. I think CommutAir has a maintenance base in ELM, hence the new service there.

As for the "all Jet" reference... In the past, CO referred to the individual hubs as "all jet". The props were removed from EWR, IAH and CLE. But they never completely left.