Hamilton jumped the Aston Martins of Lance Stroll and Fernando Alonso at the start to briefly run third, but thereafter he slid down the order, complaining at one point that even with his DRS open he couldn't challenge the car ahead.
Hamilton eventually finished eighth, while his team-mate George Russell fared even worse and retired with a cooling issue.
"My guess is that the floor is not working," he said when asked by Autosport about his DRS radio comment.
"The floor is not sucking it down. So that pushed us to go to a higher wing, and then we're just massively draggy on the straights.
"And we're losing so much time on the straights, there's nothing I can do about it, and then we're just sliding through the corners. So we have to look into why that is the case on this rough circuit."
Summing up his afternoon, he said: "Just the tyres are overheating, slow on the straights, no grip in the corners."
Hamilton said even passing the two Aston Martins at the start hadn't given him much cause for optimism.
"No, I knew that we'd have a difficult day," he said. "Nothing changed in the car from yesterday to today. So I knew it'd be a tough one.
Source: Autosport