Roger Waters and Graham Nash on The Band.

Dylan also employed The Grateful Dead and Tom Petty & The Heartbreakers as his live band, neither of which were up to THAT task.

Think about all the people The Band provided accompaniment for in the Last Waltz. Very few musical ensembles are capable of doing that. Good as they are at their own thing, being a backing band is a whole 'nother matter. Perhaps because they started life as Ronnie Hawkins band did they learn how to do that better than anyone else.

Howard Johnson was (he passed away last year) a tuba player John Simon (producer of the first and second Band albums, as well as the first Blood, Sweat & Tears, Cheap Thrills, and Songs Of Leonard Cohen albums) met when they were both members of Taj Mahal's band. Howard had previously worked with Charles Mingus, Roland Kirk, Gil Evans, Hank Crawford, and Archie Shepp. Damn ;-).

John hired Howard for the Rock Of Ages (The Band's fantastic 1971 2-LP live album) and Last Waltz concerts. Here's what Howard had to say about The Band:

"With Taj Mahal on that Fillmore circuit, we played with so many bands who were well known and had hits but who could not play by any standards I had. Yeah, they could get in the studio and make stuff perfect, but they weren't performers. And I wasn't trying to be some kind of elitist jazzhead, either."

"The Band were just so good. I don't know many guys who are that proficient who are not jazz players. These guys had a lot of flexibility. They didn't play the same thing over and over again. There was always some kind of excitement to it. Being an old jazzer, I always appreciated that. They were innovators. I think it appealed to people on a level that they didn't quite even understand."

You make it sound like the Grateful Dead were just hired hands trying their best to do what Dylan wanted them to; these were collaborations - the Grateful Dead had been doing Dylan covers at just about every show through the 80's and 90's - they knew the songs really well - so it made sense to see how it would be to have Dylan himself sing them. There was no 'task' involved, in my opinion. I quite liked the results. 

@larsman: No task involved in playing with Bob Dylan? You must not be a musician. ;-) I WILL concede that The Dead have the depth and breadth required to navigate Dylan’s waters. TP & The Heartbreakers? Nope, ’fraid not.

Have you heard Dylan & The Band’s Before The Flood live album from the ’74 tour? Play it immediately after the Dylan & The Dead album to see how the two compare.

Summer 1984 Mt Watatic in Massachusetts held and arts and energy festival. The Band headlined. Stage set up at the base of the ski hill. The sloped hill served as stadium seating,  blankets, hippies,  sunshine,  (moonshine) ,  great show! Arlo Guthrie played too. I remember getting lost driving there and stopping for directions at a farmhouse. All these geese came sqwaking and walking over trying to bite me as I walked up the driveway! That's when I learned they make good watch dogs. 

Prior to 1967, The Hawks were "just" a Rockabilly/Rock 'n' Roll/R & B band. But as wolf_garcia testified above, a REALLY good one. That all changed in 1967. The Hawks (minus Levon) spent that entire year in the basement of Big Pink, being tutored in American Roots music by Bob Dylan. They emerged the best band in the world, were offered a recording contract by Capitol Records, recorded Music From Big Pink, changed their name to The Band, and redirected the course of Rock 'n' Roll.