Wim Fissette, 36, earnest, intense, would like to tell you a "funny story". It regards on-court coaching and his first star pupil, Kim Clijsters. It's Miami years ago and Clijsters loses the first set. "Everything was going well for the opposition and the (opposing) coach came on court, talking more and more. Kim won the second set 6-0. The coach came on court again and Kim won the third set 6-0."
Fissette's story has a subtle moral: when everything's going right, coaches should kindly shut up. The Belgian - who has also coached Victoria Azarenka and Simona Halep - believes in on-court coaching but in very precise amounts.
"It mostly helps mentally," he says and offers the example of Halep. "She can tend to go to a negative feeling on court and drop her head a bit." Which is when the court-visiting coach turns from tactician to motivator and says: "Come on, you can do it."
Fissette knows the education of players has altered because coaches are more literate. They have a new text book, which in fact is real-time statistics, updated every 15 seconds, provided to them by SAP, the WTA Tour's global analytics partner.
It's a cascade of numbers - over 2,000 data entries per match are stored in their database - with players dissected into tiny mathematical parts, a sort of broken jigsaw within which secrets lie. At tournaments, coaches used WTA-provided iPads; at home, they have access to the SAP's tournament performance centre which has data from 3,472 matches just from 2016.
Fissette, a SAP coach-ambassador, is enchanted by this system. In another time, on another coaching planet, he would sit courtside with a pad in hand. On a piece of paper he drew a tennis court. On that paper court, he made markings. A dot for a first serve. A tiny line for a second serve. A mark for returns. Slowly an imprecise map of tennis grew and rough tactics emerged.
TODAY'S ORDER OF PLAY
Bethanie Mattek-Sands (USA)/ Lucie Safarova (Cze) v Ekaterina Makarova (Rus)/ Elena Vesnina (Rus)
Angelique Kerber (Ger) v Dominika Cibulkova (Svk)
Now the SAP system, with instant feedback on positioning, serve-direction, kilometres run, makes him better. "I am much more accurate, I can look for better details, I can look for patterns. You know one detail can make the difference."
For instance, he might check to see where a rival player hits when she gets a short ball. Maybe eight out 10 times she strikes it down the line. So if his player has to pick a side that's what she must choose. If she guesses right, she might win the point. And in tennis, says Fissette, the score can be "6-4, 6-3 but two points can decide a match".
Data is the new god, data is unambiguous proof which a player can't argue with, but data has to be used precisely. Fissette always has a "maximum" of "two things" ready to say to a player during a match. But knowledge doesn't always turn into a weapon. He'll tell you that everyone knows Angelique Kerber will serve wide on the ad court. It's there, it's in the data. "But she is doing it so well, it's difficult to beat her." That's also in the data.
If players need the ammunition of data, then they cannot work without the armoury of instinct. There's fact and there's also feeling. What do they sense? What hunch, based on tennis intelligence, has penetrated their brain? "This is the most important task of the coach," says Fissette, "what (and how much) information do you give your players." He knows because he's worked with two extreme types of players.
Clijsters, whom he assisted to three Grand Slam titles following her comeback in 2009, played "with her stomach". Gut feel. "If she feels on this ball I should go down the line, she goes down the line." His point is sweet: the more information he gave her, the more she would start to think. "And when do you play your best tennis? When you don't think too much." So with Clijsters, he adds, tactically he never offered more than two, three things.
Azarenka, however, "was interested in lots of information". In the off-season they'd study videos, peruse stats and conduct drills based on them. For instance, he says, when you pull Kerber wide on the backhand, she replies with a double-handed backhand that goes short cross-court. So in drills he and Azarenka would practise an answer to that.
The irony of coaching is that coaches must strive to make themselves redundant: when they teach athletes to think for themselves they have truly won. "It's easy to call a coach on court," says Fissette, but in the Grand Slams you can't. The goal thus, for coaches, is "to make the player independent".
Till then you will find his breed in the stands, most of them wearing unblinking expressions that tell wondrous lies. "I am not calm inside," smiles Fissette, yet he knows the message he sends his player must be reassuring.
He "hates losing" and he's locked in a high-stress profession which is probably why he used to take homeopathic Rescue tablets. "It gives you the feeling it's going to be all right." Of course in coaching that never lasts. And you don't need data to prove that.