PFF is not only good for the stats, but they also have some insightful breakdowns on plays/players that I've come to enjoy. This article gives more specifics on how o-line play should work in a ZBS, and given our own transition to ZBS, I thought it was a very good read. It focuses on Evan Mathis (OG) in Philly (and includes some great comments directly from him), but most of it could apply to any o-lineman in a ZBS. FWIW.