Sometimes Otz has just randomly thrown us into zones, which is something I don't particularly like. Often it's come with some bad personell for running it on the floor.
If we are going to use some zone, the above combo you mentioned (Osun should be great for this but he's really not unfortunately) plus Bob is who needs to be on the floor. The length, wingspan, and mobility/athleticism of those defenders allows us to adequately cover the floor and make passing lanes difficult. You could probably also have Gabe out there (as he's a good defender) and have Ward covering the pain. Hasan has played some EXCELLENT defense of late and this is a role he he can. Having another scorer out there (Gabe) would help offset the offensive loss without compromising the zone. Holmes is someone that could thrive with his body type but he's awareness and defensive spacing is too subpar.
When Otz randomly switches to 1-3-1 it has been VERY effective.