I don't know how much bridging there is. Put a GI on Sonnen and let him and Shogun go with BJJ rules and see if the gap is bridged. It's just a totally different game when you have the GI for grips, submissions, sweeps, etc...No gi MMA grappling and GI BJJ grappling are two totally different worlds IMO...especially when you throw in the threat of strikes.
I think the MMA grapplers are just spending more time on the BJJ side than they used to
I meant in mma now compared to back in the day. A few years back bin black belts for the most part had a HUGE advantage on the ground and rarely if ever got submitted. That isn't the case anymore