"At McLaren we haven't won the championship since 2008 and I haven't won too many races recently," he insisted.
"Every team has its ups and downs, but 2014 will be a pivotal year with the rule changes."
In the end, Hamilton's move might be seen as inevitable.
British newspapers are reporting that McLaren's relationship with Jenson Button is much closer, while the drivers themselves appear also to have fallen out.
Asked which former teammate he respected the most - Button or Fernando Alonso - Hamilton answered: "Um ... it would be politically incorrect to answer that question.
"Both Jenson and Fernando were great teammates, very competitive.
"Fernando is a two-time world champion and when I got to formula one it was a privilege to be with him."
Asked if he learned more from Alonso than he has from Button, Hamilton admitted: "Sure, because he was my teammate in my first season, so I noticed his telemetry, his way of driving. I learned a lot from him, yes."