Jenson Button said he was "a sitting duck" in the final laps of the British Grand Prix as he tumbled from sixth place to 13th in his home grand prix.
The McLaren driver and team-mate Sergio Perez had come through to sixth and seventh places as others pitted during the safety car for Sebastian Vettel's stranded car. But Button said the combination of a late restart and cars behind on newer tires was a worst-case scenario for McLaren's current issues.
"When the safety car came out at the end, I had quite old tires and was just a sitting duck," he said. "I couldn't get any tire temperature. That's one of our issues anyway and when you've got no tread you definitely can't get tire temperature.
"I was just waiting for people to pass me. It was tough."
Button was also confused by the McLaren's tire behavior earlier in the race, when he struggled with graining on the harder Pirellis then found the softer medium option far better.
"The first stint we went for the primes because nobody else in front was on them, but that was actually the one that grained - front and rear - for me so we had big problems in the first stint," he said. "We just had to wait until a lap we could pit and put the other tire on.
"I was much happier on that tire -- strong pace and no graining... work that one out..."