what is going on with the tyres, and things are further confused by Dorna changing their mind, having directed Bridgestone relatively recently to produce tyres that wore out as with F1 tyres at the time to improve the spectacle.
It was said pre-race that 2013 tyres would be used at COTA, with the not very convincing explanation that there were insufficient 2014 tyres, and it has been said they are looking at re-formulating the 2014 tyre anyway. The PI tyre debacle was not all that many races ago either.
A wider range of tyre choices to suit different bikes and riding styles would seem in order, but if Bridgestone have no competition, conflicting instructions and are providing tyres for free or close to free, then the tyre situation is perhaps not very surprising, and the control tyre is looking very much like a false economy.
I doubt Rossi has developed a propensity to wear out tyres in 8 laps after all these years, so I would be looking for factors external to him, but I am not quite sure how occurrences in this race fit in with opinions expressed as facts about tyres being saved by sliding or Jorge's purported wrecking of the Yamaha chassis geometry being more influential than the talent and endeavour of the bloke riding the lead HRC bike or the engine the Honda engineers have come up with.
Tech 3 bikes seemed to perform well so perhaps Yamaha are on the right track for the next formula.