Yamaha rider Maverick Vinales says his mounting tally of troubled MotoGP weekends between wins are "a big drama in my head right now".
After qualifying ninth on Saturday, Vinales said he did not "want to talk more about tyres because it looks like I am the only one talking all the time".
Vinales started the season with back-to-back victories in Qatar and Argentina, before crashing out of the Austin race, intimating that tyre inconsistencies could have been a factor.
He then had "no feeling" in the front tyre during the Jerez race, but won at Le Mans and finished second at Mugello.
However Yamaha struggled again at the low-grip Barcelona throughout the Catalunya Grand Prix weekend, having not joined Honda and Ducati in testing at the track last month, with Valentino Rossi finishing eighth and Vinales 10th.
Asked what happened, Vinales interjected that he was "slow" and added: "I really don't know.
"This morning, with 15-lap [old] tyres I did a 1m46.1s. This afternoon, with new tyres, a 1m46.7s going to crash.
"I really don't know. I don't know what to say. I tell everyday the same [story], so I don't know.
"Our bike is good. That's what I can say. It was good in Qatar, Argentina it was good.
"All the races, our chassis, it's not this. The problem is not the bike.
"From first, leading, to 16th now [before other riders' problems] is a big drama for me.
"Because I go home, I don't know what happened, I'm not really motivated and I have to do many races.
"Honestly, it's not only the result of today, it's the result of many races."
Vinales maintains the championship lead, but his advantage over Barcelona winner Andrea Dovizioso has been slashed from 26 points to seven.
The Spaniard said his team was also perplexed, having struggled as a unit all weekend and being beaten by Tech3 satellite riders Johann Zarco and Jonas Folger in fifth and sixth.
"For me it's a big drama in my head right now, because I don't know what I'm doing wrong," he said.
"I'm doing the same as in Qatar, Argentina and the other races. I'm riding the same way.
"[The team] also don't understand what happened today, and many places.
"In Argentina I did 1m39.7s in the warm-up, 1m39.6s in the race. Mugello I did 1m47.2s in the warm-up, 1m47.6s in the race.
"Here, I did a 46.1 in the warm-up and I did only one 1m46s in the race. One. It's something amazing.
"At the end, I was riding really like Moto2. I could not understand. Honestly, on the straight, it was amazing."