You don't have to be Ross Brawn to know that track position at Monaco is king. So even if Hamilton had requested a stop the team should have told him to stay out. They had data that Hamilton didn't. They knew Rosberg wasn't going to stop for example. The chances of losing a position to the slower Ferrari had to be no better than the chances of stuffing up the pitstop. Mercedes even claimed that they didn't have GPS so they didn't know exactly where Vettel was. Why would you stop under these circumstances?

I put this one squarely on the team.