DL's
Contract of Carriage (like most airlines) explicitly disclaims liability for failure to operate on schedule.
Delta is not responsible or liable for making connections, failing to operate any flight according to schedule, changing the schedule or any flight, changing seat assignments or aircraft types, or revising the routings by which Delta carries the passenger from the ticketed origin to destination.
The chances here of them offering anything other than a customer service goodwill gesture (of SkyMiles) are
very low, especially since the initial delay was weather-related.
I'm not that familiar with BA's Avios, but are you sure there's no way to redeposit the miles for an unused award? (IOW, I think DL is the only airline with the 72-hour rule...)