Featuring a new lineup, an open-ended definition of Americana, and the backing of a major label, Band of Horses’ third album is a game changer. What began as a partnership between Ben Bridwell and Mat Brooke has since blossomed into a five-piece band, with Bridwell serving as the only link between the group’s 2006 debut, Everything All the Time, and the present. It’s only natural, then, that Infinite Arms sounds wholly different from the albums that came before it, both of which mixed guitar-driven rock with dusty, jangled folk. There’s still plenty of folk to be found here, and Band of Horses bang their way through “Compliments” as a concession to their rock fans. Infinite Arms is a borderline pop album, though, dressed up in flannel and facial hair to disguise the fact that these melodies are, with few exceptions, the sweetest of the group’s career. There are harmonies galore, simple fifths and thick, Sacred Harp-type chords that beef up Bridwell’s vocals while drawing parallels to Fleet Foxes and the Beach Boys. At times, it’s hard to separate Band of Horses from such influences; “Blue Beard,” although downright gorgeous, cops its verse from Smile-era Brian Wilson and its bridge from the Starland Vocal Band, and “Older” is the country-rock single Gram Parsons never wrote. But the album’s willingness to sample from so many different genres -- roots, soft rock, alt.country, power pop, indie folk -- makes it sound like nothing else in 2010, and Band of Horses connect the dots by layering everything with canyon-worthy reverb and cinematic guitars. For those who let it sink in, Infinite Arms could be a contender for the year’s best summer album, not to mention the band’s most cohesive album to date.