Orrin Evans

Colin Marshall / NPR

It isn't typically news when a jazz group makes a change in personnel. But The Bad Plus isn't a typical jazz group, and its announcement, this time last year, landed like a bombshell. In short: Ethan Iverson, the band's pianist, would be leaving to pursue his own projects. Orrin Evans, an esteemed peer, would be stepping in. For a group that has always stood for musical collectivism — and never accepted any substitutions — this was a shakeup of existential proportions.

Josh Goleman / Courtesy of the artist

For the last 17 years, The Bad Plus has been a model of musical cohesion. Its members — bassist Reid Anderson, pianist Ethan Iverson and drummer David King — have been an indivisible front, welcoming the occasional guest but never a substitute, according to the strictest ideal of a working band. As the saying goes, it has always been larger than the sum of its parts.