While I fully believe Vinales with regards to the front tire not feeling the same as this has been going on since Michelin has returned last season. I question his claim that the tire inconsistency being retaliation for his complaints about COTA's front tire.
There's different ways of looking at the situation in my opinion, and no I don't buy into Vudu's claim this is the Spanish mafia at work. Jerez has been a near 50/50 proposition of whether the factory Honda or factory Yamaha would win at the circuit over the last number of years.
One way of looking at it is simply that Michelin's quality control is ..... I believe this partially because any manufacturer that knowingly manufactures a mismatched tire profile on the front and rear can't be trusted to provide a quality racing tire according to the needs of the riders.
But where it becomes a less certain prospect is that Ezpeleta did at least desire having the sort of tire degradation F1 had during the period of 2011 thru 2016. We've discussed on here about Phillip Island 2013 being a sort of possible trial run for a high degradation tire that was soundly rejected by all. Rather than have a high degradation tire, the next best way of achieving unpredictability would be to engage in a planned inconsistent manufacture of tires. This would be the easiest way to create unpredictability from race weekend to race weekend. Last season's multiple race winners situation will not be seen again any time soon as the teams with the most money to spend will come to grips with tire changes far quicker than any satellite team will. I think this is partially why Honda decided to supply "factory" bikes to their satellite teams. They frankly need the data --understandable given the nature of the 2015 and 2016 seasons with regards to the RC213V's issues-- and the more data they generate across the HRC riders, the greater the chance of coming to grips (no pun intended) with the tire characteristics as it relates to the RC213V. Yamaha only has their factory machines and Tech 3, whereas Honda has 3 satellite bikes, possibly a 4th if LCR decides to field a second rider or not in the near future. This is also why I'm not particularly bullish on KTM's prospects in GP. They can say whatever they'd like, but the reality is Honda and Yamaha have had a stranglehold on the sport for the last 35 seasons and breaking that is not going to be done in 2 or 3 years if it can be done at all. But they do have a commitment to trying to do this, hence why I won't write them off completely.
Like I said, I don't doubt what Vinales has said with regards to the feel of his tires. It may not really be aimed at him for retribution/retaliation for complaining, but to just try and spice up the racing as much as can be done now that order has been once again established in year 2 of the spec ECU.
Another way of looking at is also that Yamaha managed to .... up their chassis for the first time in quite a number of years which is unusual given they don't engage in radical/extreme changes with their chassis. Something we don't know is how good is Vinales at giving proper feedback and who is really giving the most feedback internally - Rossi or Vinales? Yamaha chased down...not exactly a dead end, but an alley that doesn't appear to be the right way. Why they did is really the pertinent question that has yet to be answered. I'm not going to say that Yamaha is infallible as teams large and small do get things wrong all the time, but it's just uncharacteristic of Yamaha in the modern era. The chassis situation could also be further exacerbated by the tire situation...and my feeling is it's not really down to one thing over the other, but several factors that when combined cause problems.