LONDON • John McEnroe fears Novak Djokovic's burgeoning spirituality could be draining the Serb of his "killer instinct".
The American tennis legend, who wrestled with his own volatile personality for much of his career, says of the one-time shirt-ripping beast of the Tour: "From an emotional standpoint he perhaps felt he wanted to bring in somebody who wants to give people a lot of hugs. That does not necessarily translate to having that killer instinct.
"It does not automatically lose it, but you don't want to get into a situation where it is all peace and love and then have to go out and try to stomp on somebody's head in competition."
That is a not-so-oblique reference to the influence of Djokovic's spiritual adviser, Pepe Imaz, the former Spanish fringe player he brought on board last year.
Imaz sits quietly in the world No. 4's box nowadays, a beatific figure of calm looking down on the drama of his friend's increasingly erratic performances.
He told the Spanish sports paper Marca in May: "This type of work became known with Boris Becker leaving (last December). A very important person. It is logical it draws attention. And so (people) jumped to the concept of hugs, love, and Pepe Imaz. It's the same as before. He is having a moment he does not like, he would like to win more matches. And he's working to do it."
McEnroe observes: "I am imagining it is a work in progress. But it is a combination of things - whatever is going on off the court. He had an injury (a year ago), a let-down, and all this stuff contributes to it. I kept thinking it was going to get better."
But it all went horribly wrong in the saddest meltdown of the summer, Djokovic, the defending champion at the French Open, giving up in the third set of a quarter-final to the relentless young Austrian Dominic Thiem.
He left the clay of Paris for the grass of London not like a contender but disillusioned and lost, with nobody at his side but Imaz, whose tennis expertise resided some way in the past.
Djokovic's angst lingers as he awaits confirmation that his other new mentor, Andre Agassi, will be with him at Wimbledon next week.
So anxious is the three-time champion about another assault on the title that he is risking embarrassment in the high winds of Eastbourne this week to knock his tennis back into shape. Djokovic has not played on grass between the French Open and Wimbledon since 2010.
Agassi will not be at Eastbourne. If he comes to Wimbledon it is unlikely to be for the fortnight.
He stayed for less than a week in Paris and he spent much of his time there promoting a brand of coffee and the tournament's watch sponsor before leaving on the eve of Djokovic's collapse against Thiem.
The Serb was so dominant for so long that even this slight decline has people wondering if he is getting ready to quit.
He and his wife, Jelena, are expecting a second child in August, yet the joy and self-assurance on court that he derived from the arrival of their first child seems to have evaporated.
The world No. 117 Denis Istomin put him out of the Australian Open in the second round; Nick Kyrgios beat him back to back on hard courts in Mexico and California; Alexander Zverev blitzed him in Rome; then Thiem destroyed him. The young gunslingers scent blood.
McEnroe, who will be as fascinated as everyone else watching the story unfold at Wimbledon from the BBC commentary box, says: "He's 30, but we were talking about him blowing past (Roger) Federer (in terms of grand slam wins) only at Wimbledon last year. Or at the very least (Rafael) Nadal. Nobody is sure what is wrong really."