While the Houston economy has been stagnant overall and the oil industry has declined year over year, passenger emplanements have grown slightly for the Houston airport system from June 2015
United is yielding domestic traffic to competitors American, Southwest, and spirit. Routes that were previously served by 737's have been served by 70 and 76 seat aircraft. United has been yielding long haul flying to its code share partners Lufthansa and ASA are flying super and large wide body aircraft to connect star alliance passengers to united's hub.
What is worse is LAX, not over staffed but United marketing and operations are yielding market share to competitors and code share partners.
Houston is the #3 and LAX is the #2 O and D markets and that traffic is being ignored or put on the back burner.