Collins completed his switch to Preston this week, having made one Wolves appearance this season - in the Carling Cup against Swindon, when he scored the decisive penalty.
"Neill made a significant contribution to the club during his time here and played a major part in our Championship success last season," said McCarthy.
"We all know what a whole-hearted and committed player he is and how he never gave anything less than 100 per cent every time he stepped out on the pitch.
"Even when he wasn't involved over the second half of last season, he was still the consummate professional, training as hard as ever and playing his part in the squad.
"I can completely understand his need to play regular football and I am sure everyone at the club would join me in wishing him all the best at Preston."