McLaren finished in third in the constructors’ championship during the 2012 campaign, while Button was down in fifth in the drivers’ standings with many perceiving the car to lack reliability due to a series of issues throughout races.
However, Button was also critical of the McLaren’s speed, particularly through the middle third of the season.
“Sometimes you do get failures and you’ve got to rectify the issue,” Button said. “But the most difficult part for us was before the summer break when we just didn’t have the pace.
“The reason why we were not fighting for the title isn’t just the reliability issues, the pace in that period of time wasn’t good enough compared to our competitors. We have had reliability issues, but when you actually look at it, the problems have all been at weekends.
“We did 1400 kilometres at the young driver test and didn’t have one issue at all, so we have been a little bit unlucky, I think.”