Red Bull are in a frightening anti-Renault campaign at the moment. Fact manipulation is severe, Max is right on it, must be why Horner and Marko love him so much.
Just as a reference - Silverstone map.
When you compare race speeds from last year and this year:
And qualy speeds as well (disregard Dani Ric 2017 qualy, he had turbo failure in Q1):
You understand that every team went for more downforce this year (where the lap time comes of course) sacrificing top speed a bit. Ferrari made the biggest progress due to great work on aero efficiency and PU, but Max has clearly had more downforce/drag than Dani Ric (who had to use DRS manually in Q). Also, Max lacked DRS in the race, where this speed deficit comes from. Look where Hamilton was with top speed in race last year (without DRS) and this year 20kmh up.
Red Bull chose to go Ferrari 2017 - max downforce, sacrifice efficiency. Just like Ferrari last year - they were top dogs in Monaco (and very likely will be in Hungary and Singapore) and they struggled the most (so far) in Silverstone. It's a ctrl+c, ctrl+v really.