If you think the D was the main reason we lost you weren't watching. I'll type this AGAIN: SD scored 10 points in drives that started from their side of the field. 28 points came off 3 TOs and a failed OS Kick.
Junc, at some point the D needs to make a meaningful stop, like on the possession with about 7 mins left where they gave up two 3rd Down conversions, one of them a pass play of 50 that set up a TD immediately thereafter.