In both cases the performance was similar. With earthworks I simply didn't give a damn about the job, so just pecked the ground unenthusiastically. With burnout it was as if petard went off, but instead of earbuzz you get numb to planning, focusing and executing. I actually felt bad about it, but doubt you'd see much behaviour difference from the outside.
So I'd wager the lack of motivation is a serious handicap in both cases. Sure, "anyone can dig a ditch" but I dare you try doing it for a day if you are not into it. Similarly I was already an experienced developer at the point of burnout, and the job at hand wasn't challenging at all.