Caterham team owner Tony Fernandes says that Heikki Kovalainen's form during the final two races of 2013 played a part in the Finn missing out on a 2014 seat.
Kovalainen raced for Caterham between 2010 and 2012 and remained with the team as their reserve driver for 2013 after failing to retain his race seat.
Kovalainen was linked with a return to a race seat at Caterham but was overlooked in favour of Formula 1 returnee Kamui Kobayashi.
Fernandes says that Kovalainen's two race stint for Lotus at the end of 2013 - when he replaced the injured Kimi Raikkonen - hurt the Finn's prospects.
"Obviously we would lie if that we said it didn't play a part," Fernandes told Autosport.
"It was a whole mixture of a lot of things but in any decision there are pros and cons.
"I put it out to various team members - there were those pro Heikki and those pro Kamui and I had to make a choice."
"We have to move on, we have to be a little bit cold, if we want to be successful," he said of parting ways with Kovalainen.
Kovalainen progressed through to Q3 on his race return in the United States Grand Prix last season but finished 14th in the race and matched that result a week later in Brazil.
Kovalainen has yet to reveal his plans for 2014.