“Blue Ocean Floor,” the album’s closer, could have been lifted straight off Kanye West’s “808s & Heartbreak.” Over a stuttering electronic sample, Timberlake luxuriates in an unvarnished croon that mines the silkier shades of his voice. It trails off into a gurgle, subsumed in water. The JT of 2006 would never have ended a song, much less an album, like that.