The German led from start to finish at Pinehurst and eventually triumphed by eight shots to win his second Major and continue his resurgence in the 2014 season.
After nearly three years without a tournament victory, Kaymer won the Players Championship at Sawgrass last month, after which McGinley spoke with the 29-year-old candidly about his game.
McGinley told reporters: "It was nice to hear the debrief, but it was also very insightful for me. It was very clear from what he was saying to me and what he was saying to his caddie that this wasn't a rejoicing, shouting from the rooftops, we are back on the top of the summit again. It's a start.
"And it's no surprise he's followed it up six weeks later to win a Major. He was very clear that this was the start of a surge and he's been proved right. He gives a lot away about himself when he gives a press conference, he's very insightful about himself and he's very honest."
The Irishman has hinted that Kaymer's loyalty and flexibility could make him an important member of the European team when they aim to defend the Samuel Ryder trophy against the United States this autumn.
"He's a popular guy. Yes, he minds his own business and does his own thing but he's a very loyal guy, loyal member of the team. And he's an easy guy to pair. He's not high maintenance. He doesn't need to play with one player or another. He's kind of happy to be guided, whatever the captain says. That's what we saw with Jose and Monty [Colin Montgomerie, captain in 2010], as well. There's no reason to think he will be any different with me, hopefully anyway."
Kaymer, who has played in two Ryder Cups previously and sunk the winning putt in the memorable comeback win in Medinah in 2012, currently holds an automatic qualifying spot for the tournament.