Disagree that there isn’t much difference in return with a deadline trade vs offseason trade, at least with a player as good and unique as Corbin Burnes.
Burnes at the deadline would be the most coveted player available and would return much more than the offseason due to the extra control, and the fact of there being no competition with FA signings.
San Diego, Philadelphia, Texas, Toronto, NYY, would be 5 teams off the top of my head I could see overpaying for Burnes at the deadline.