Looked to me like Viviani didn’t go full out in the intermediate sprint. I suspect Quickstep, who don’t have GC hopes, let Dennis take 1st and Pink expecting payback later. In fact, it could very well happen at the end of this stage, with BMC keeping the pace high so QS can conserve their train and not worry about chasing down escapees. I wouldn’t be surprised to see Dennis helping out with his TT skill. The best way to avoid getting caught up in a crash during a sprint is to be in the front.