For many artists, a retreat into the Great American Songbook arrives near the end of their creative growth – it’s an easy way to stay in the public, cater to an aging fan base, and perform songs that remain evergreen in their perfection.

Not all artists, however, are themselves a living, breathing Great American Songbook, and so Bob Dylan’s recent turn to covering old songs by the likes of Frank Sinatra and Cy Coleman remains a curious career move. He brought this cabinet of curiosities – a set largely centered on these covers alongside his recent Tin Pan Alley and Dixieland-influenced originals – to Thompson’s Point in Portland on a fine summer’s evening Saturday, performing an easygoing concert appropriate for a venue with hammocks hanging in back.

Audience members hoping for a hits-laden set of classics had their expectations dashed early (the eternal Mavis Staples, just a week after her 77th birthday, better obliged with an opening set of Staple Singers chestnuts such as “Respect Yourself” and “I’ll Take You There”), but in Dylan’s defense, he can no longer pick a guitar like he did on “Don’t Think Twice, It’s All Right” or articulate a torrent of language like he did on “Subterranean Homesick Blues.”

Instead, adorned in a snazzy black suit, he guided his crack band through an airtight suite of songs, occasionally playing a few bars on the piano or unleashing a blast of notes from his harmonica.

All things considered, his voice was in stellar form. He now wields it more like a paintbrush than a scalpel, but he’s also up to the task of the emotive nature of these Sinatra songs. There is a degree of irony in a man who has been derided for his singing voice for half a century becoming a romantic crooner in his mid-70s. Dylan puts his own spin on the songs, singing in his road-weary grumble and aiming endearingly for the high notes while his band plays a tender slow-dance behind him. It’s surreal, yet affecting, and one suspects Dylan is drawn to the songs so he can focus on the feeling and the sounds of words rather than the literal meaning.

He brought the same approach to what few classic songs he played, shifting the vocal emphasis to the ends of the lines in the “Bringing It All Back Home” gem “She Belongs to Me” and finding new space between the words of “Tangled Up in Blue.” His original songs of the last two decades opened up in a live setting, blending easily with the covers. “Early Roman Kings” is framed by a generic blues shuffle on the album, and became far more robust and epic on stage – lit up by a haunting piano lick. The bluegrass-influenced “High Water (For Charley Patton),” from 2001’s “Love and Theft, “grew into a swell of end-times atmosphere.

It’s impossible to say if he’ll return to writing original songs (the last time he devoted himself to covers this much, in the 1990s, it led to a fertile period of writing), but it’s clear that this is not the final stop for him so much as the most recent phase in a career full of very distinct phases. The sophisticated blend of material led to a rich concert experience.

For the most part, the audience agreed – although at times there was a palpable sense that people were itching for more classic material. There were a few mumblings, and a steady trickle to the exits beginning as early as the intermission. This is not new to Dylan, who has made a career of confounding audience expectations. Once upon a time, frustrated audience members shouted “Judas” at him. On Saturday, one heckler shouted, “C’mon, Bobby, play some Street Legal!” The times, they have a’changed.

Robert Ker is a freelance writer who lives in Portland.