One difference you need to take into consideration is downtowns growing population now exceeds 13,000 and excepts to continue to grow. Lots of new downtown housing on the works, new hotels and new restaurants and retail. All this can do is help to make sure it will not fall again.
As far as UA is concerned CLE still has more flights then any non hub airport and I find it interesting they continue to fly to destinations that has other competition. In particular BOS, LGA, LAS, MCO and now FLL and RSW seasonal.
Lets face it the airlines seem to want there hubs in the huge population markets
and with consolidation there are less of them. ATL,ORD, EWR,IAD,JFK,LAX,SFO,DTW,
and DFW. Not sure about SLC.
Somewhat less of the extent PHL,IAH, DEN, and CLT. DL continues to cut at CVG and PIT,STL, and MEM lost the hubs for the population scenario.