Holden, 27, currently in the USA recuperating from knee surgery, has played just one game in the last 17 months.
But boss Coyle wanted to remind Wanderers’ player of the year in 2010-11 that he is still valued at the club.
He said: “I’ve sent him over our home and away tops — and his training kit. I hope that will act as a little boost for Stuart.
“And, hopefully, sooner rather than later, he’s going to be using it. We think the world of him.
“I spoke to him the other night. But the last thing I’m going to do is put him under duress, in terms of when he’ll be back in action.
“I just wanted to find out where he’s at. He’s doing well. He had a clean-out op three weeks ago, and he’s feeling better for that.
“We have to give him as much time as he needs. He sounded in a great place, that’s the type of character he is. His first concern was to ask after everybody else.”