Spent 6 hrs in ATL when I missed a connection, when inbound flight was delayed.
Delay component 1: DL late in boarding flight
Delay component 2: Short ATC hold on taxiway
Delay component 1 lot longer than Delay component 2.
If I had had the time lost in Delay component 1, I would have made my connection.
DL records show only "ATC delay"
Suspect this sort of obfuscation is not unusual.