McLaren's Jenson Button says strategy mistakes and a lack of efficiency prevented him from fighting for a podium in Sunday's Belgian Grand Prix.
The Briton, 33, ran as high as third, but the team dithered between a one and two-stop strategy and a late second pit stop dropped him to sixth at Spa.
"I'm not sure we got it right with strategy," said Button.
"There were areas where we expected to be a bit better - efficiency was one of them and that hurt us quite a bit.
The 2009 world champion added: "If we had that we could be fighting with [Lewis Hamilton's] Mercedes for third place."
McLaren are on course for their first winless season since 2006, with a podium proving difficult to achieve this season.
Button's fifth place in round three in China remains the team's best finish of the season, but at Spa, where Sebastian Vettel took victory for Red Bull, the car looked much more competitive.
"We have got some work to do," added Button. "It's nice to be racing with Mercedes and one of the Red Bulls [Mark Webber].
"We beat two Lotuses fair and square and one of the Ferraris - so yeah we're making progress.
"In terms of performance, I'm pretty happy with the car. There is lots of room for improvement but we know exactly the area.
"The feeling of the car and the balance was nice and I really enjoyed driving it.
"Our aim was to fight for podium. We didn't quite do that but we were fighting at the front and finished just 13 seconds off third."
Button was third with 10 laps to go when the team decided to pit for a second time, ending his hopes of a podium finish.
"We pitted too early on the first stint," said Button. "We went to a two-stop and then tried to go back to a one but there was no way were we going to do 12 more laps on that set of tyres.
"So we pitted which was best thing to do. It's better to be chasing rather than being overtaken."