I might add - it surprises me that CO did not take some of the IAH cancelled flights (aircraft) and add additional flights say from CLE. What are they going to do with the aircraft - just let them sit at remote (non-hub airports) and give everyone refunds.

They could for example added a flight or two from CLE to SAN to replace a couple of the IAH to SAN - these flights were already very full - and likely half the people were connecting.

You could do this for example by taking a flight from SAN to IAH and resend to CLE. Then fly it back and forth to CLE-SAN for two days, then return it SAN to IAH.