Deemed surplus to requirements by Chelsea, the midfielder pointed to his goals and assists for Manchester United as proof of his contributions on the pitch.
Juan Mata says "creative players always get blamed" when things go wrong and says he is more productive for Manchester United than he ever was for Chelsea.
The midfielder was voted the Blues' Player of the Year at the end of both of his two full seasons at Stamford Bridge, but fell out of favor under Jose Mourinho.
After spending the first half of the 2013/14 campaign on the bench, he was sold to United in January 2014 amid suggestions the coach had doubts over his workrate.