This is the paragraph in post 2 (Paris) that I referenced in my response:
The truth in advertising test should be applied in these statistics. At least when you book on Southwest, you know that you're going to be on a Southwest Flight. The Southwest stats indicate the true stats for their 3,500 daily flights. Some carrier's are only reporting on 1,300 flights, yet if you go their website, you book a flight on what you think is a mainline flight it most likely turns out to be an express flight. The paint job is nearly the same, the same inflight magazine is used and it's got a flight number that says its a mainline flight, yet if the express flight is late, the mainline carrier takes no responsibility for it and blames the other carrier. Are those stats included in this report? How is that fair.
The simple fact is that the network airlines operate much more complex networks but they also provide the details that are needed for each of the operators. Your point may be somewhat valid that you don't know how OT a flight on a regional carrier is because the operator might work for two airlines, but honestly, do people make a decision to purchase a ticket based on any carrier's SYSTEM OT numbers? Doubtful. If you fly LGA-ORD, you want to know the OT for THAT segment. How DFW-IAH does is immaterial to your decision if you don't intend to fly it yet the system average includes that.
Likewise, WN's OT is clearly going down as they venture into the congested and weather prone NE and midwest. I don't care what WN's system OT is if they don't operate BOS-BWI OT and conversely, I could care less how BOS-BWI fares if all I ever fly is PHX-LAS.
Statistics can be used to show lots of stories but if you ask the right question and ensure the answer you are given answers the question you asked, statistics can be very useful.
Now that WN has committed to 738s, it seems a given that their ground time will have to go up on flights operated w/ those aircraft, esp. in NE cities.
Again, WN is becoming less distinct and more like the other carriers.