They are told what should be a safe time and stay near it if a driver fails to reach q3 based on the time he was told it's not his fault it's his engineers for telling him a wrong time.
I'm pretty sure the 2 different engineers will say 2 different times based on their judgement.
hamilton was 2 tenths faster maybe because his delta time was 2 tenths faster.
We all know the teams like to save tyres
Yes but he set a time, things change, the track was improving throughout the session, they had time to come back out. Vettel and his engineer would have decided if they were coming back out, and Hamilton and Rosberg, Rosberg and his team clearly chose not to thinking they were safe, they weren't. Its a mistake, again you were saying its basically a conspiracy and the team screwed Rosberg, which was laughable.
Its actually very likely that Hamilton/Rosberg were given about the same time to go for and Brawn said Rosberg just had a bit of a bad lap. Obviously the time they aim for isn't 0.0001 seconds below the cut off so be a couple tenths slower and its going to be risky but could very easily still go through.
Driver and team make these decisions and together they decided they were safe. I find it hard to believe a team would go directly against the drivers wishes if he chose to go out. Regardless of what his team told him, he can see the times himself, all drivers monitor them, and part of being a driver is making decisions. Both Rosberg and the team decided they were safe.. they weren't, thats it. No conspiracy, Hamilton has comfortably beaten Rosberg all season and a Merc 1-2 is FAR better for Hamilton than a Merc 1-11. Drivers and teams make mistakes and get tactical calls wrong, thats all that happened.
Have we ever seen a driver in 2nd place 4 minutes before the end of Q2 knocked out? Mercedes were wrong in this instance but I don't think they were foolish.
Early times often tumble, there have been plenty of times the big boys have come out done their safe laps and tumbled all the way down.. the few times there are huge upsets its more likely traffic or a bad lap when they rush out at the end, but I'm fairly sure there have been drops that big before.
As you say, they did get the call wrong(thats the whole team, Rosberg and his engineers) but it wasn't absurd to think they would probably make it and could save a set of soft tyres.
He could have course have come out with 3 mins to go and ended up caught in traffic and still not made it, in general though that car is awesome in qualifying... but there will always be mistakes, lets just hope for Merc's sake its one of only a few this season.