DL 5334 then AA 4599 at Philadelphia
Detroit → Philadelphia → Boston
Timetable, Philadelphia time
11:37DL 5334 from Detroit at the gate
14:10AA 4599 to Boston leaves the gate
2 h 33 apart on the timetable
The last days
DL 5334 and AA 4599 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.