"Worst?" - The problem is that many stations can't justify mainline service or, if they could, it would be at 1/4-1/3 of the frequency. The 2007-09 time period demonstrated the folly of flying empty aircraft and then cutting fares to fill seats.
It would be great if CMH and other stations could justify larger and more frequent aircraft, but they can't. This is about the local economy, not about some abstract decision by UA or DL (and just wait to see the proportion after the US acquisition of AA is complete).
The fact is that people who travel for work would prefer four flights/day on smaller aircraft rather than a single mainline aircraft at sometime when it can be sent out and back for a quick run.