If Mercedes lost in the battle for the first line, it means that the strategy was not winning and was wrong, because it cannot be said that Red Bull is a cut above the speed and really everything was decided at the pit stops
I don't think that Mercedes did mistake with strategy. I doubt that with different strategy they would have won race. Max even with older tyres was able to keep Lewis behind. Though, on final laps Lewis was very close, with open DRS maybe we would have different outcome.
I don't think Mercedes made a strategy error, either. They did what they could, with the options they had. And yes it was all decided at the pit stops.
The crucial thing here was the role of the second driver. Because Red Bull had Perez up at the front, and Mercedes didn't have Bottas there, it gave Red Bull a 2-1 car advantage, which meant they could control exactly when Hamilton stopped.
They stopped both Verstappen and Perez early, which meant Hamilton had to stop quickly in order to remain ahead of Perez, otherwise Red Bull could just have used him as a slow-moving roadblock whilst Verstappen disappeared into the distance. Alternatively, if Hamilton had stopped first, they could have kept Perez out, run him long, and done exactly the same thing... either way if you have an extra car, you can use it to control the other team's driver.