The Dubliner's disqualification from the Abu Dhabi HSBC Championship last Friday led to him commentating rather than playing as Kaymer marched to a staggering eight-shot win on Sunday.
"He's probably the most formidable player in the world when he is leading," said Harrington.
"He seems to intimidate the rest of the field into believing that if he gets in front he is going to win."
The victory means Europe now has the two top-ranked players in the world in Lee Westwood and the 26-year-old USPGA champion.
That has not happened since 1993 when Nick Faldo and Bernhard Langer - another English-German pair, of course - led the way.
And it means Tiger Woods starts his season in California this week outside the top two for the first time since October 2004.
He was the one who used to be virtually guaranteed to go away from the field once he got his nose ahead.
But after taking a lead into the final day of a major 14 times and winning them all, Woods was overhauled by South Korean YE Yang at the 2009 USPGA Championship.
And last month, of course, he was four clear after 54 holes of the Target World Challenge and lost in a play-off to Graeme McDowell, keeping him winless all season.
Whether it is an aura he can regain remains to be seen. In two weeks' time he will be facing Kaymer and Westwood at the Dubai Desert Classic.
Northern Ireland's Rory McIlroy will hope to be a factor there as well - it was the scene of his only European Tour victory so far - after finishing a distant runner-up this weekend.
The 21-year-old was delighted by his move from 12th to world number seven in his first outing of the year, but Kaymer was in a different league.
"Very impressive - he was in total control of his ball," stated McIlroy.
"He just goes about his business and gets on with it. He's a class act, he really is, and deservedly world number two."
It was Kaymer's third win in the event in four years - he was second the other time - and that prompted the organisers to give him the trophy to keep.
"It's just the perfect course for me," he commented after playing the last 60 holes without a bogey and finishing an astonishing 24 under par.
"I hit a lot of fairways and my putting was amazing. It was just one of those weeks when everything (apart from a shank into water on the 12th hole of his opening round) goes my way.
"I never expected my career to go this fast. There was not a lot to improve this week, but there's always something and I'll be working on my game before playing again."