I also think Mercedes waited as long as possible before bringing Hamilton in under the VSC fearing that if they brought him in at the start of the VSC, Ferrari would just have brought Vettel in as well. They played it well I thought. Bottas did a great job as well seeing as that engine had done all the races so far this season
Think after the first three seconds of his excellent start, Bottas did a poor job overall today. Could have overtaken Hamilton, but instead backed out and ended up causing two DNFs (he got lucky it wasn't three including him). Yep, he held up Vettel a bit but he only really pulled one defensive move - which was decent, and had the desired effect, but he shouldn't have been so far back that he would be in position to hold up Vettel.
Of course though - with the benefit of the hindsight of knowing his engine was going to go - it was more of less the best possible race from him, from Mercedes' perspective. Took out one of Hamilton's rivals and Verstappen, who could have made the first lap more dangerous for Hamilton. Then protected Hamilton by being slow. Then got two thirds of a race worth of data on the upgrade. I'm sure they'll take it.