Ever since bursting onto the music scene with his 2001 album “Room for Squares,” John Mayer has been slowly evolving his musical and lyrical styles. Although he began with a much more pop-centered style, he has incorporated more and more blues into his work. Now, with his newest album “Battle Studies,” Mayer has taken another step into blues-pop fusion with heartfelt lyrics influencing an album filled with loneliness as well as glimmers of hope.

Mayer described “Battle Studies” as “a heartbreak handbook,” and it shows. Many of the songs deal with both the sadness that comes with the end of a relationship as well as the fragile hope that one day there will be something better that comes along. The opening track, “Heartbreak Warfare,” begins with the sounds of a crowd and an orchestra warming up for a concert and quickly dives into an atmospheric, smooth sound that defines much of the album. Mayer sings “Clouds of sulfur in the air/Bombs are falling everywhere/ Its heartbreak warfare,” describing the battle of a couple in the midst of breaking up. With soothing vocals, a subtle but affective solo and great rhythm, the song is one of the best on the album.

The next track “All We Ever Do Is Say Goodbye” is filled with rich harmonies and calm acoustic guitars and piano, bringing attention to the emotional lyrics and honesty in each line. “Half of My Heart” is easily the most country-styled song of Mayer’s entire career, not because of his vocals but simply because of the instrumentation, but guest vocals by Taylor Swift helps, too. It’s more upbeat than the previous songs and feels like a hybrid between Tom Petty and Fleetwood Mac.

The first single, “Who Says,” is easily one of the weakest songs on the album, and it’s stripped down sound, while relaxing, is forgettable. “Assassin,” however, is the most surprising and standout song of the entire album and is sure to be remembered as one of Mayer’s greatest songs. He took risks throughout the track and succeeds on all levels, with percussion that sounds like the winding up of a jack-in-the-box, layered back-up vocals and chose to have barely any guitar on the first half of the song all making it unique and powerful.

It is, however, followed by the weakest track on the album: “Crossroads,” a cover of the classic Robert Johnson blues track in the spirit of Cream’s blistering live cover from 1968. Mayer’s version is spacey, shallow and almost emotionless and is a speed bump in the great flow of the album.

“War of My Life” gets back to the heartbreak and hope and continues Mayer’s blues sound with lots of atmosphere and layers added for good effect. “Edge of Desire” is easily the most heartbreaking song on the entire album. Every word and note aches and yearns. Like “Split Screen Sadness” from “Heavier Things,” there is an unresolved hurt and need that leaves the listener wowed by the song and Mayer’s earnest lyrics.