Bob is so insistent upon reworking his own songs and making them sound different every time out that I suppose it does make sense, in a way, to characterize his performances as "covers" of his own material.

Is he just so bored at having sung the songs so many times that needs to hear himself do something different?

I've attended about a dozen Dylan concerts since he "went electric," and have been disappointed with his performances about half the time. The other half-dozen times, he was great, and provided the transcendant experience that only comes from live music at its best. I'm not always one to automatically dismiss his rather idiosynchratic approach, and in fact I really enjoy it when it works. But, for me anyway, it's hit-or-miss; it doesn't always work.

I mean, I've never regretted going to one of his shows, even the ones where his singing left me cold, because the band is always outstanding and Bob is always, at least, well, interesting.

But I emphatically do not belong to the "No one sings Dylan as well as Dylan" school of thought -- to me, some of these covers we're mentioning are definitive performances of these wonderful "bulletproof" songs. It may be arguable whether they're "better" than Dylan's original recordings, but they're memorable, they're excellent, and they're generally superior to at least some of Bob's own experiments in reinterpretation.