"There is a lot of Dan Carter in Richie Mo'unga," MacDonald said. "Very rarely do you see him rattled at all, at any level. He's very casual, he enjoys a laugh, he's a bit of a joker and I think you need that temperament as a 10 because there's a lot of pressure.
"I watched the [America's Cup] sailing this morning and they just seem to have ice cold blood in their veins under immense pressure, and that's Richie. He doesn't seem to be fazed and for a young guy to control a team like the Crusaders, with a lot of big personalities, a lot of big strong men who have played a lot of rugby - to run the ship as confidently as he does at his age is a real credit to him.
"He's got a big future and he's starting to realise the potential that a lot of people saw in him when he was at school."
Gatland has brought some very good No10s on this tour of New Zealand, including Farrell, Johnny Sexton and Dan Biggar, but it's significant that it has been their opposites making the headlines. Gatland's son Bryn bamboozled the Lions with his kicking game in Whangarei, Perofeta belied his 19 years and the fact he was starting for the Blues for the first time at Eden Park, and his replacement West scampered under the posts for the winning try.
There was a note of caution from MacDonald about the expectation on Mo'unga, but there is no doubt that everyone at the franchise, and perhaps even at New Zealand Rugby, believes the young man has a big future.
"I don't want to put pressure on Richie and say there's Dan Carter peformance brewing tomorrow, but there are similarities to his game," MacDonald said. "When I was playing Dan was starting and he had the same attributes.
"Richie has had a fantastic year for us - he bounces back from injury well and he's really resilient. He reviews his performances really harshly. He's tough on himself and wants to be better but he has a nice balance in his life. I think he's going to get better and better and at one stage we'll see him in a black jersey."