Jon Rahm hasn't got a curl in the middle of his forehead, but in every other way he reminds me of the little girl in Henry Wadsworth Longfellow's famous poem.
You know the one: "When she was good, she was very very good, but when she was bad she was horrid." It pretty much sums up the hugely talented Spaniard.
There have been weeks during this season when the 23-year-old has played golf from the Gods, not least on his way to finishing fourth in the Masters or when he collected the CareerBuilder Challenge prize back in January to briefly go second in the World Golf rankings.
At other times it has come from the devil, especially on his way to missing the cut at Carnoustie in The Open where his tantrum slamming a club into the ground would have made John McEnroe look even tempered.
So the first thing to say about backing him for this week's US PGAat Bellerive Country Club in St. Louis is that it comes with a health warning. If it goes wrong, it will go spectacularly wrong.
Rain at Bellerive will suit him
But at the same time I can't help thinking that 30.00 for the heir to the Spanish golfing traditions of Seve Ballesteros and Sergio Garcia looks a pretty tasty price for a player whose talent is surely close to a Major breakthrough.
After a week of rain, topped up by a deluge on Tuesday when more than an inch fell in 24 hours, Bellerive is going to suit the big hitters and Rahm puts a great big tick in that particular box.
He was fourth in the annual charity competition held there yesterday, whacking his ball a brilliant 320 yards down the 10th fairway (Bryson DeChambeau was the winner with 331 yards).
He's also 15th on the driving distance charts for the PGA Tour this season, just to prove that powerful hit was no fluke.
His form coming into the weekend is about right, neither spectacularly good nor bad at Bridgestone last week as he tied 17th, let down by a fairly average final round of 73.
Wears his heart on his sleeve
But by then he'd shown enough glimpses of his prodigious talent - this is a boy who spent a record 60 weeks a world amateur number one - to suggest he could be timing things right to put up a proper challenge in the year's final Major.
He's 4.30 for a top 10 finishand given how the event is going to favour the big hitters that's a decent bet.
Backing Rahm will be a bit of a roller coaster ride, but no more than say Rory McIlroy who is half the price at 15.00 and has also shown he has frailties trying to get the job done in the big events.
Rahm's temperament causes controversy. He's a fiery character on the course, with all his emotions on display, and inevitably there are those who suggest how much better he might be if he could keep his anger under control.
But I like all that emotion in a 23-year-old and at the moment I think it's all part of his game. There will be more than enough time for taming the wild animal inside him but just now it's a force that drives him on.
Just hope it's a weekend where he's good - because then he'll be very, very good.