Even if you didn't know that saxophonist Matana Roberts, drummer Chad Taylor and bassist Josh Abrams developed their Sticks and Stones trio concept at Fred Anderson's Velvet Lounge in Chicago, just hearing the first few jabs of skittering percussion that open Shed Grace lets you know they're deep in the AACM bag. That's not the problem. It's how the three support players approach group improvisation - each of them so concerned with leaving the others space that no one steps up to lead the way forward - that leaves Shed Grace sounding strangely static. Instead of a free-flowing exchange of ideas, we get a passive/aggressive stand-off. Sticks and Stones play the Music Gallery Friday (July 16).