The Mercedes driver had gone into the Suzuka race hopeful that the team could build on some promising potential shown in practice with a new set-up direction for the W15.
But he was put on the back foot almost immediately from the restart of the red-flagged race after a minor clash with Leclerc in the opening sequence of corners left him with car damage.
That meant he suffered from excessive understeer, and explained why he was so happy to move over for team-mate George Russell, who had closed on him in the first stint, a few laps later.
Speaking to F1 about whether the car had not delivered what he'd hoped for in the race, Hamilton said: “I mean, the car is never what I would [have] hoped it would be. It's never what we'd hoped it would be.
“I got some damage in the first stint in the restart with Charles, and I had massive understeer, like huge, huge understeer. So that's why I decided to let George by, because he seemed quicker.
“I just couldn't turn the car, and it took us two stints to finally dial more and more wing in to make up for that loss. Last stint I was better, but it was too late. I had 10 seconds to regain.”
Source: Autosport