Starting from 10th on the grid for the Canadian Grand Prix, the 32-year-old ended up stopping on three occasions when every other driver pitted once or twice, finishing 16th.
It is now just two points from the last four races after starting the season with a win in Australia and second place in China.
In stark contrast, McLaren team-mate Lewis Hamilton won for the third time around Montreal's Circuit Gilles Villeneuve to become the seventh different winner from seven races this year.
As for Button, he simply has no answer to his woes as he said: "I just had no speed at all. I couldn't look after the tyres, I had no pace. There was nothing there.
"It's been the same at the last couple of races. I don't know why it is. Normally it's something I'm pretty good at.
"I haven't got a clue what is going on. Every time we think we've some good ideas we don't seem to make any progress. I don't know why that is.
"I'm also driving around one and a half seconds slower than the leaders, one is my team-mate, and I don't know why because I can't push the car any quicker. I'm not that slower than them.
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"So this was a terrible race, I've never had one like it, and they seem to get worse and worse,
"I'm pushing the car to its limits and yet I'm so far off the leaders. It's a little bit confusing.
"Every time you jump in the car you're confident and excited it's going to go well, and every time you make changes you think you are going to improve. But it's not happening.
"I'm confused and very lost. I don't really understand what is going on at the moment."
Button dismissed suggestions regarding the Pirelli tyres, adding: "Definitely not, it's not a tyre issue.
"I can't be the only person that can't drive on these tyres. It's impossible.
"They're normally something I can work with and get the best out of more than most, but it's not the tyres.
"Looking at it I did three stops and most people did two or one, yet it's normally the other way round."
Button was at least gracious enough to express his happiness to Hamilton and the team for a win that keeps McLaren in touch with Red Bull in the constructors' championship.
Button added: "First of all congratulations to the whole team. Lewis did a good job and it seemed like the strategy worked out for them in the end."