The 55-year-old, who is delighted to return to the Brodies Champions of Tennis tournament in Edinburgh this June, was equally comfortable yesterday to give a frank assessment of the challenges facing Scotland's favourite son, Andy Murray.
Due in part to time off from the tour to undergo back surgery at the turn of the year, and coachless after his split from mentor Ivan Lendl in mid-February, the 27-year-old from Dunblane finds himself reduced to No.8 status in the rankings and without a tournament victory to his name since that epoch-defining, ghost-busting triumph at SW19.
While acknowledging the additional uncertainty about how the spring and summer months will unfold for the Scot, McEnroe sees much to embolden him, even if it means going canny on clay in order that he arrives at Wimbledon and the US Open in prime condition. Come SW19, McEnroe feels that Murray, regardless of changes in his corner, should be primed to come out swinging, with the pressure off, in defence of his title.
"Certainly at this stage he is at least a notch or two below where he was when he won Wimbledon," said McEnroe. "A lot of things that were unexpected, at least to me, have happened. He missed around three months before he played Australia due to surgery. Then with Ivan and him splitting, that was another surprise. So I think it is hard to tell where he is at mentally.
"Coming into the clay season, that is the most difficult part of the season for him," McEnroe added. "So it is going to be interesting to see how he handles it, how seriously he will take that, how much he will play, how much he will do. Because in certain ways I guess he might not want to risk playing too much, if he is not all the way back physically and mentally, in the hope that by the time Wimbledon comes around he is back to 100% and has a shot at retaining his title. He has to go with his instincts, because his instincts have got him into a position where he has been able to win slams."
Tennis players provide enough amunition for amateur psychologists to have a field day. It remains to be seen how severely Murray has been affected by recent events, but McEnroe feels dwelling upon his achievements to date - the US Open and Wimbledon wins, and Olympic gold in 2012 - can provide a source of inspiration for the Scot.
"I don't know exactly what happened [between him and Ivan], but I am thinking that must have been unsettling," said McEnroe. "He could pick up someone now, or he could continue to go along with the same group he has had, minus Ivan, I really don't know. But it is not like he is going to forget how to play or the things that Ivan told him. So it doesn't necessarily make a lot of difference, although I think their record spoke for itself.
"But if I could give Andy one piece of advice; assuming he is healthy, I would simply have him reflect on his successes the last couple of years. He doesn't need to ramp up the pressure - no-one can ever take away the US Open, the Wimbledon and the Olympics. He certainly belongs in the top four. I wouldn't want to wish anything bad on other guys, but overall he has more to his game and he should be there.
"There is always going to be pressure for him to win Wimbledon, but I think it is going to be significantly less, just because he has won, because he has broken that jinx. He has finally been able to lift the trophy. He has two majors under his belt and won the Olympics there as well so I would be shocked if it was anywhere near the same level of pressure."
If there is an inclination to write off Murray on clay - none of his 28 career titles has been on the surface after all - it is interesting to note that Rafa Nadal, who, after a year of peerless excellence, has now been beaten by his countrymen David Ferrer and Nicolas Almagro in back-to-back tournaments on his most cherished surface.
"It is just that there are other guys who grew up on it, and their game is better on that surface, just like his is on others," said McEnroe. "Murray's movement is the thing that separates him from a lot of other guys and I don't think that advantage is as pronounced on clay. He loses that edge and it takes a little bit of his confidence away. I don't know what happened in the Davis Cup, and I know he had played a couple of days in a row, but I was still surprised that he lost rather routinely to Fabio Fognini. If you want to make inroads on clay, that is the kind of match you have to win."
As for the serious business of the senior tour in Edinburgh next month, McEnroe is praying for better weather than that which ruined the final day's play last year, after a sweltering first couple of days. Tournament organisers have specially extended the roof for this year and insist a "suitable refund policy" is in place in the event of any delays, and McEnroe for one hopes to reward the fans who stoically "rolled with the punches" last year. With the likes of Ivanisevic and Henri Leconte also confirmed, elder statesman Super Mac is usually slated for one day of doubles and a couple in the singles.
"The field we had was great, the energy from the crowd was great, although the weather could have been better," he said. "I like playing in the doubles with Tim [Henman] and some of the younger guys . . . but these days I am probably better off playing with some of the guys closer to my age."
As for his accommodation for the tournament, he has located a nice little budget motel nearby. It is called Cromlix House Hotel.