I rolled the Flowers video forward slightly from when the above shot was taken, to just after Flowers has caught the ball, and he's moved his foot to where Posey's is (exposing about a third of the base. In this case, it probably isn't enough as Blanco is about to start his slide, but if Blanco was more to the outside or further from the plate, maybe he doesn't get the call.
Speaking of that, I wonder how long the catcher has to provide the lane. If, for example, Blanco had been 30 or 40 feet away when Flowers caught the ball as he did, with his foot blocking the plate, then shifted to give Blanco a lane when he is still 20 feet away, is that long enough? Or is blocking the plate off completely at any point the runner is coming down the line illegal? I honestly don't know at this point.
I guess I'd like to see the rule modified so the "fair" result comes out of the play. In the case of the 2 plays above, the throw beat both guys by a mile, and neither really had a chance to be safe regardless of where the catcher is set up. If it's a closer play and the runner didn't have a lane to the plate, I'd give the benefit of the doubt to him and call him safe, but I hate seeing a guy given a run on a play like today where he's clearly out under the old rules. Not sure if what I've described can be translated into a written rule, but I'm guessing we see some tweaks over the next season or two to give better guidance to the catcher, runner, and umpires.