After introducing a raft of upgrades in Monaco, Mercedes seemed to be on an upward trajectory with a double podium in the Spanish Grand Prix and another podium place for Hamilton in Canada.
But two weeks on Mercedes took an alarming step back in Austria, with Hamilton and team-mate George Russell finishing eighth and seventh respectively.
Hamilton said the Brackley team's Red Bull Ring woes were "definitely surprising" after its recent resurgence as his W14 felt worse to drive than in the previous two rounds.
"I definitely didn't expect to be as bad as we were today," he said.
"I don't really have an answer for it, really. It's definitely surprising but the feeling of the car was very much the same as the feeling I've had all last year, so in that respect it's not the biggest surprise.
"[The car] was definitely different compared to the last two races. The last two races were way, way better than today."
Source: Autosport