Alpine hid its true potential in testing at Sakhir by not running soft tyres or low fuel, but Gasly picked up the pace in second practice, when he was an encouraging seventh.
However, while team-mate Esteban Ocon progressed to Q3 and earned ninth place on the grid, Gasly fought understeer and traction issues and was slowest of all in Q1.
"It's clearly a one-off," he said when asked by Motorsport.com what had gone wrong. "I don't fully have the answers now.
"But I looked for more front the whole weekend, and struggled with understeer. I don't know why, it was just way too extreme for the conditions, and was a bit all over the place on all the exits.
"I was very comfortable all through practice. I was just fine-tuning from session to session. But the general car balance has been always the same every single time I've jumped in that car.
"In quali you kind of go for it. And all the references or expectations that I built up through the weekend just disappeared, and it was very different in terms of car balance. I just didn't put the lap together and it's a shame.
"We'll look to understand what's happened, clearly not the ideal start, but I know there's way more based on what we've showed and just need to understand a little bit why I wasn't able to extract it today and focus on tomorrow.
"I'm confident there's way more in it than obviously what we show today."
Asked if there was an issue with tyre warm-up, he said: "It wasn't ideal in the out-lap. And I guess everybody can pretty much say the same. So at the end, you're looking for small details. I'm not going to blame the out-lap, it was just a poor lap and things just didn't click.
"It was mainly like just the traction, couldn't really get out of the other corners, and it's just very opposite car balance than what I had in practice.
"I don't really have the answers, but we'll look into it later today and also the weekend, but now we need to focus on the race."
Gasly admitted he was surprised by the speed of some the cars that kept him in 20th and last.
"We definitely didn't expect these guys to show that much pace," he noted.
"But I mean, for now, it's mainly looking at ourselves. It's pretty much the first time that we went all out, and just the car behaved very differently to whatever I've experienced before."
