Doyle grabbed his third goal of the season to set up Wolves' impressive 1-1 draw at Everton, a game where they arguably did enough to have won.
Russian recruit Diniyar Bilyaletdinov ultimately denied Wolves victory but McCarthy took plenty of positives from the trip to Merseyside, not least the performance of Doyle, who moved to Molineux from Reading in a £6.5million deal.
He said: "Doyle has been a 'signature' signing of the summer, our big signing. And he has proved to be worth every single penny of the money we paid.
"He is a terrific player and has started to score goals. There will be more, I am delighted with him."
McCarthy was philosophical about the outcome, but was less than impressed by referee Stuart Attwell's decision to send off Austrian substitute Stefan Maierhofer in the dying minutes, describing it as "harsh bordering on the downright disgraceful".
The former Rapid Vienna man was first booked after a tangle with Tim Cahill and was then shown a second yellow after an incident involving Toffees goalkeeper Tim Howard, in which the American appeared to have committed the more serious offence.
McCarthy was disappointed his side were unable to record their second away win in the Premier League and added: "The feeling amongst the players is that we should have had three (points).
"I am disappointed by not hanging on for the win. We deserved more with that performance, I was very pleased with them and the way Kevin Doyle took his goal.
"But we have been 'done' out there. Doyle was fouled in the build-up to their goal, even if we could have done more to stop it.
"There were loads of plus points, the only bad one was conceding a goal in the last few minutes.
"(Defender) Jody Craddock was terrific, he had seven stitches in his forehead and he still kept heading everything away, a real old warhorse out there for us.
"Everton had some chances but (goalkeeper) Wayne Hennessey had a terrific game. He has got better and better and matured as a player and a person, I can't speak highly enough of him this season."
Doyle was equally upset with the eventual outcome, saying: "We created a lot of chances, played 4-4-2 and looking very positive with me and Sylvan (Ebanks-Blake) back together.
"He has finally got himself fit and he had chances, sooner or later they will go in.
"Ronald Zubar was great on his Premier League debut at the back, and Wayne was terrific in goal. But he has been all season.
"We are disappointed with the draw, but that surely is a good thing when you are at an intimidating place like Everton.
"I'm pleased with my start at Wolves. But I missed a lot of pre-season due to an operation and then missed the first few games of the campaign.
"But I'm fit and beginning to play OK. Wolves spent a lot of money on me and now I am able to start repaying them for that.
"It is good to be feeling sharp and getting goals. We have done better against the bigger teams and a point at Everton - who finished fifth last season - underlines how we are improving."
Everton boss David Moyes did not try to paper over the cracks in another unfamiliar Everton display, the side crying out for the creative play of Mikel Arteta and Steven Pienaar, both of whom will still be missing for Thursday's Europa League tie away to Benfica.
He said: "It was good to see (Ayegbeni) Yakubu back after injury, he looked as if he was almost at his best, and we needed it because we were not looking as if we would score in a month of Sundays.
"But we have been playing that way for a month or so. We need to get through this and get back to playing with some form and a better style."
Everton have embarked on a punishing seven-match spell, with injuries still hampering their progress.
Moyes said: "It is a tough schedule, but if you want to be successful you know you are going to have a lot of games.
"That is what we want, and that is what we have to contend with. We are looking forward to it, and the game in Lisbon is a chance to produce a better performance than we did against Wolves.
"The travelling for the lads playing international matches this week has been tough, some going to the other side of the world.
"But they are paid well to do so, and they enjoy playing for their national sides. They are also paid well by their clubs, so they have to come back and do it for us, too."