Skittish. That is the adjective that repeatedly springs to mind when watching Rory McIlroy playing in the majors of late.

Next week’s PGA Championship at Quail Hollow will mark three years since the 28-year-old’s fourth and most recent major win.

Since when Jordan Spieth has won a Masters, US Open and, most recently, Open, while the likes of Dustin Johnson, Jason Day, Sergio Garcia and Henrik Stenson have all opened their major accounts.

To say McIlroy is impatient for more success would be an understatement. This much we know from watching the Northern Irishman at Augusta National.

In theory, the Masters should be the major that most plays into his hands. With its four reachable par 5s and a premium on those who can flight soft-landing iron shots, there was a theory that McIlroy would win every other year here.

And it may all have been very different had it not been for that 2011 collapse when a four-shot lead heading into Sunday evaporated with a closing 80.

That was the first time that JP Fitzgerald’s credentials were seriously questioned – McIlroy could be seen wiping away tears after driving on the 13th, his chances of the Green Jacket over for the year.

Could JP have offered more support – or tough love – to his man when he needed it the most?

Ever since then McIlroy has found new ways to fail to get to the top of the Augusta leaderboards.

The pattern is set. It’s clear that the Masters dominates his thinking in the months leading up to the season’s opening major. Unhealthily so, you might say.

You sense he feels that he has to play flawless golf; that he must take every single birdie and eagle opportunity the course offers; that a dropped shot is a fatal blow to his chances.

When he fails to go out in 33 on Thursday, he looks unduly intense. Thereafter it is two steps forward and one step back. He makes a catalogue of unforced errors – seemingly one for every time he gets back to the brink of contention.

At the end of the week, despite it all, he still finishes in the top 10 and that makes him – and us – wonder once more what could have been.

His last four Masters finishes are T8, 4, T10, T7.

Now, even more worryingly, the disease is spreading into the other majors.

It was exactly the same at Birkdale a few weeks ago. The dreadful start, the comeback, the chasing down of a distant lead, the unforced error, another comeback, the late disaster and still a top-10 finish.

For most tour pros, two major top 10s out of three so far this season would represent a fine achievement.

McIlroy, though, is aiming higher.

And that’s why it is not a surprise to see him part company with JP, his friend and long-time partner on the fairways.

The critics will say that it is McIlroy who misses the putts and hits the occasionally wild tee shot. That the player is ultimately responsible for club selection and strategy. Which is true as far it goes.

But anyone who has ever played the game knows how much of it takes place in the head.

Yes, Seve Ballesteros used to tell his latest caddie that his jobs were “to turn up, keep up and shut up” but you only have to watch the way that Spieth and Mike Greller work together to acknowledge that there is much more to it than that.

In a sporting world of marginal gains, McIlroy is wondering, rightly in my opinion, if a fresh perspective from his bagman might just change his mood on the golf course.

That’s not to say that JP is a bad person, or even a poor caddie, just that it’s time for a change, time to try something different.

It is analogous with trying a new putter.

We all know – although often choose to ignore – that it is the Indian not the arrow, and we acknowledge the old maxim about a shoddy workman blaming his tools.

Yes, there may well have been nothing wrong with your old putter. However, a new one can change your outlook.

Think of it as a dead cat bounce. It might be nothing more than the equivalent of a struggling football club sacking their manager a month before the end of the season (and usually replacing him with Harry Redknapp).

But if it changes the mood then it’s often worth a punt.

It’s hard to change the way you putt; it’s easier to change your putter. Similarly, it’s hard for McIlroy to change the way he thinks; it’s easier to try a new caddie and – he hopes – derive the benefit of a fresh perspective.

It won’t be an easy job for whoever is appointed as JP’s replacement.

McIlroy is headstrong. He is a sportsman more in the mould of Seve than Nick Faldo in that he plays with emotion. Mood is everything to him. He can come and go very quickly. He’s impatient.

As he says himself, he is taken by this famous Tom Weiskopf quote: “When I’m playing well, I can never imagine how I ever played so badly. And when I play badly, I can never imagine how I played so great.”

McIlroy added: “I think that’s how fine the line is in golf, between playing great and playing poorly.”

McIlroy’s curse, at the moment, is his intelligence and self-awareness.

I believe he is firmly of the opinion that, at his best, he can beat Spieth and Co.

I also believe that although he can see what’s happening to him on the golf course, he has concluded that with his current team he isn’t able to change it.

Hence this big decision.

For this proud, stubborn man, it won’t have been an easy one to take. He and JP have been together for nine years and enjoyed massive success.

I suspect there is little acrimony between the two and that McIlroy’s parting shot would have been along the lines of ‘it’s not you, it’s me’ and ‘we can still be friends’.

Right now, though, I’m not sure that McIlroy needs his caddie to be a friend as much as a figure of authority.

He needs someone who can make him more stable on the course. Who can stand up to him when required.

Starting at Quail Hollow next week, a venue McIlroy loves, and which offers him an instant chance to turn around a season that otherwise looks destined to be remembered for frustration and what-ifs.