Somehow, over the past several decades, the voice of Willie Nelson has become part of America's aural landscape. Some of that may be due to marketing, and more than a little owes to his distinctive talent. But it may also stem from his disengagement. Original material, an Irving Berlin chestnut, the Austin phone book: He sings it all the same. That nasal monotone, those hurried little drop-offs at the end of phrases, that wispy, evaporating vibrato on long notes, pretty much define the sum and substance of every Nelson performance.

This works in his favor on two levels: by stamping his identity onto each performance, and by not scaring the public away with anything spooky, emotionally challenging, or otherwise George Jones-like.

But albums like Milk Cow Blues also make it harder to take Nelson seriously. The artist who once revolutionized country music with projects like Red Headed Stranger is now content to dust off some old blues and a handful of his well-worn classics, summon a few heavyweight guest stars, and call that a concept album. There's almost no point to running down the list: Dr. John sounds just like Dr. John on "Black Night" and "Fool's Paradise," ditto for B. B. King on "Night Life" and, of course, "The Thrill is Gone." Kenny Wayne Shepherd's riffs all over "Texas Flood" leave us missing Stevie Ray all the more. And so on. At least Susan Tedeschi's incredibly flat vocals on "Crazy" get our attention.

"It's flooding down in Texas, all the telephone lines are down," as noted in "Texas Flood." The marvel of this performance is that Nelson managed to phone his parts in anyway.