Pirelli found that 90% of the rear tyres used in free practice for the 2016 Grand Prix had been cut by the bolts securing kerbs to the ground not being drilled into the ground far enough, while Jenson Button and Nico Rosberg expressed concern over the lack of run-off areas which would be dangerous in the case of an incident such as a high speed puncture or mechanical failure. Valtteri Bottas was forced to miss the whole of Free Practice 3 when a drain cover came loose and caused significant damage to his Williams FW38. The first practice session of the 2019 Azerbaijan Grand Prix was cancelled when George Russell hit over a lose drain cover. Many drivers praised the circuit for the challenge offered by its mixture of long straights, slow technical sections and no margin for error due to the proximity of the walls. In 2021, Rosberg criticised the location of the pit lane entrance adjacent to the main straight, calling it "one of the places I always found the most dangerous of the whole year". Formula One race director Michael Masi disagreed with Rosberg, saying the venue "fulfils all of the various safety requirements that the FIA has within its regulation requirements.".