Formula 1 supremo Bernie Ecclestone believes Fernando Alonso "gave up a little bit" over the 2013 campaign and was looking to leave Ferrari.
After being warned about his conduct by Ferrari president Luca di Montezemolo in July, Alonso was then the subject of public overtures from McLaren on a weekend it emerged he was also a possible candidate for the second 2014 Red Bull seat.
Ecclestone believes Alonso was keen to move, and that his form suffered as a result.
While the two-time world champion ended the year as Sebastian Vettel's nearest challenger, he surrendered 116 points to the German over the final nine events.
Alonso was also outqualified by team-mate Felipe Massa five times over the final eight races.
"I've been a little disappointed in Fernando, because I'm a big supporter of him and Ferrari," Ecclestone wrote in a foreword to the official Formula 1 season review.
"I thought he gave up a little bit, which is proof he was looking for another team."
Ecclestone said he was also unsure whether Ferrari could provide Alonso with a championship-winning car, adding: "I don't know whether the team is not competitive because of him or because the people running the team aren't getting the job done.
"He certainly deserves a car that's capable of winning races. Whether that Ferrari is or not, I don't know."