While few faults can be found with the Italian's basic technique there have been hints that he does not hold up well under pressure. Rocca's performance in the Ryder Cup singles at The Belfry two years ago is cruelly cited as an example. Taking three putts at the 17th he lost to Davis Love III after being one up with two to play. Rocca has made the team again, but more than once this year he has fallen back into the pack when well in contention.
So much of golf is in the mind that nobody can be sure where the players are coming from. They can hit it straight one day and all over the place another. They can start full of confidence and feel like running for cover before the round is completed.
Rocca is no different to any number of leading players but an unfortunate reputation now precedes him. In yesterday's circumstances the betting was that he would choke. He looked cool enough on the first tee but as someone said his insides were probably as knotted as spaghetti.
A genial man, Rocca does not walk around the course, he saunters. It is the measured gait of a tenor coming out to perform at La Scala. Neither is there much in the way of sartorial elegance. He must be the only player on tour who wears brown shoes with blue trousers.
In the minds of Italian sports fans golf figures about where netball does in this country. It draws fewer spectators than football teams in Serie A are guaranteed to get for their training sessions. Consequently, only four Italian sportswriters were on hand to record Rocca's progress.
Here and there along the ropes, spectators, probably Scots of Italian descent called out encouragingly. Occasionally there was a cry of Forza Italia.
Rocca played the first comfortably. Drive, short iron, two putts. Par. He wandered off, looking as though he was taking a constitutional. All he needed to complete the picture was a stick and a labrador.
A long wait at the fifth tee, almost 10 minutes, affected Rocca less than his young partner. He has hit better second shots but by comparison Campbell's effort was a disaster. When the New Zealander went wildly right, all of 100 yards, a debate over line of sight gave the Italian a further 10 minutes for reflection. He made par from a difficult lie and when Campbell dropped another at the next they were level.
The wheels seemed to be coming off when Rocca bogeyed the 10th but he held the round together grittily, picking up a birdie at the 14th then proving a lot of cynics wrong with a brave recovery from the gravel alongside the notorious Road Hole. After some deliberation Rocca gambled on bouncing his ball over the bank. He executed the shot brilliantly and then made par from four and a half feet. Who said Rocca does not possess the heart for it?
At the last, needing a birdie to enter a four-hole play-off with John Daly, he put paid to that slur for ever. Rocca's second at the 18th may be one of the worst shots he has played since his days as a caddie in Bergamo. A 24-handicapper could have been expected to make a better job of it. Striking behind the ball Rocca sent it only half the intended distance. Left with a huge putt, his last chance seemed to have gone and it could be imagined that Daly, watching with his wife from behind the 18th green, was rehearsing the acceptance speech.
Astonishingly, Rocca conjured up one of the great moments in Open history. The ball was in the hole from the moment it left the 42-year-old Italian's putter. When it dropped he fell to the floor in exultation and then rose with a smile on his face and the trace of tears in his eyes.
To paraphrase the words of Alf Ramsey when the 1966 World Cup final against West Germany went into extra time, from having the Open won Daly had to go back out there and win it again.
People strolling on the course at 6am on the eve of the Open saw a lone golfer out practicing. It was Daly. We should have known then that the former wild man was deadly serious.
Daly confirmed that in the play-off, going a shot up on Rocca at the first extra hole before pulling completely away from the valiant Italian. It was all over for the man from Bergamo but he finished with a birdie and a smile and will be stronger for the experience.