Red Bull has been on the back foot all weekend at the Marina Bay circuit, with both Verstappen and team-mate Sergio Perez failing to progress to Q3 in qualifying on Saturday.
Verstappen could do no more than 11th in his car, with team-mate Perez 13th, and the Dutchman said changes made to the car after a "not too bad" FP3 ultimately derailed his challenge.
Asked by Sky F1 if qualifying was worse than he expected, Verstappen said: "Yeah, for sure. I knew that it was already going to be tough to put it on pole, but this I didn't expect.
"Also, I think throughout the weekend we have been struggling.
"I think FP3 was not too bad, but then we tried a few more things on the car for qualifying where it tipped it over to the car being undriveable again, where car was massively bottoming out in the braking zones and every time I wanted to brake deep and hard, my front wheels were getting unloaded.
"So, like I said on the radio, it was just a shocking experience because also just trying to lean on the car in low speed, just constantly no speed, no traction. Just really difficult to drive."
Verstappen has recovered from low grid slots before to finish on the podium this season, like in Saudi Arabia where he came from 15th to finish second.
But the Dutchman concedes he doesn't have a car good enough to fight for the podium on Sunday.
"No, for sure not," he replied when asked if he had any hopes of a rostrum in the grand prix.
"I think anyway here is much less about actually having a good race car. It's a bit like Monaco.
"You put it all on qualifying and even with deg it's quite difficult for anyone to really pass you, because the tyre wear is not that high.
"So, it will be a long, tough afternoon. So, hopefully not too many safety cars and the race will be quite short."
Verstappen faces several investigations for potential impeding infractions in the first two segments of qualifying, though admits his evening was "so messy" that any grid drop "doesn't matter".
"We'll speak to the stewards," he said. "Honestly, at this point, it was just so messy that it doesn't matter if we start from P11, P15 or last.
"At this point, it's just more important we understand why it was so bad. That will be way more important than trying to score a couple of points this weekend."
