"It makes an impact in the dressing room when you sign a player of that calibre," Jones told United's official website.
"He is such a talented player on the ball. He has definitely lifted spirits in the dressing room and especially in training. We want to impress and show him that we are what we are, that we are one of the best teams to be at.
"He came in against Cardiff. He has done well and I am sure he will be a huge asset and fantastic player for Manchester United, hopefully for many years to come. He sees the pass that sometimes no-one else sees. If he continues to make them, I am sure we will soon be climbing the table."
Mata joined Chelsea from Valencia in 2011.