Mata was returned to the Blues' starting XI in midweek after being left out of Jose Mourinho's matchday squad for the derby date with Fulham on Saturday.
Mourinho has challenged the Spanish forward to tweak his game and prove that he can become an influential figure for the Stamford Bridge outfit once more.
Assistant coach Holland feels Mata did everything asked of him at the County Ground, with Fernando Torres' opening goal coming from a low shot he saw parried by Wes Foderingham.
"Obviously a lot has been made of the Mata situation because he's a high-profile player," said Holland, who also revealed Marco van Ginkel suffered a potentially serious knee injury and Ramires a hip problem.
"The message to all of our attacking players from Jose from day one has been they need to contribute offensively in terms of their production and of course they have to contribute out of possession and defend.
"That's been the challenge not just to Juan but all of our attacking players.
"In Juan's case, if you look at his performance here, he made Fernando's chance and was involved in the goal. Those two moments - goal-making and goal-scoring actions.
"And then in injury time he's conceded the final corner of the game supporting Ryan Bertrand in the left-back spot, which is how he was all night.
"Tonight, for sure, we're very, very pleased with Juan's contribution with and without the ball."
Copper hopes his Swindon players will take important lessons from a meeting with Premier League opponents, but feels they offered enough in a 2-0 defeat to suggest that they can move forward in a positive frame of mind.
He told Sky Sports: "We tried to play. We played some decent football at times without really hurting Chelsea.
"We had a goal disallowed which looked offside. If that had gone in it would have been interesting, but I felt as though we showed what we are trying to do.
"We tried to play, we tried to move the ball quickly and at times we played some good stuff. But we didn't threaten the goalkeeper enough, whether that is down to us being sharp enough around the box or Chelsea defending, I don't know.
"But full credit to Chelsea, they came here and their attitude was spot on and if they do that then it becomes very difficult.
"You are always looking to get to 20 minutes and stay in the game. I felt we did that reasonably comfortably, but at any time they can open up with world class players and hurt you.
"We could probably say that we could have defended better, but let's give the credit to the forwards - good movement, good finishes, and that's what you get from those players."