And believe it or not, Halep's tactical changes weren't that complicated.
"She raised her game, raised her level," Stephens said in a press conference after a 3-6, 6-4, 6-1 loss Saturday in Paris. "Not much you can really do about that. I competed the best I could, and the better player won the match today. Obviously, I saw my chances in the second. You learn from it. You move on. You try to be better next time."
Did Stephens succumb to the realization she was in a position to win a second Grand Slam title?
"I think it was just, when you're up a set and 2-0 and you see the finish line, and I think you get ahead of yourself," Kamau Murray, Stephens' coach, told ESPN.com. "All of a sudden, you look up, and it's 2-2 again, and you're down 3-2, and the calmness sort of left. It's a lesson learned. She had a lot of opportunities in the second, from 2-2 all the way to 4-all, every game was 30-all, and she definitely had the match on her racket. Next go around, she's definitely got to do a better job of finishing."
Halep said she told herself to relax, enjoy it and not worry about the possibility she might lose a fourth Grand Slam final. "Then when I started to win games, I said that last year [it] happened to me, same thing, I was [a] set and a break up [against Jelena Ostapenko], and I lost the match," Halep said. "So I said there is a chance to come back and win it. So I believed in that and my game was more relaxed. I could make more things on court, and that's why I could win."
Halep turned the momentum around by changing tactics, lengthening rallies, cutting back errors and making Stephens work even harder in rallies. As she got tight, Stephens became more passive, suddenly rolling in serves at two-thirds pace. She went from winning 77 percent of points on her first serve in the opening set to 43 percent in set two and 44 percent in the decider.
Halep's coach and ESPN tennis analyst, Darren Cahill, who had been concerned early, said the change got to the legs of Stephens. "Simona was having trouble finding ways to win easy points," he told reporters. "In the end, that probably worked a little bit in her favor. Because there was no easy way to win points. She had to grind for every point, and I thought Sloane, you could see late in the second set, getting a little bit tired.
"She made more errors than she did in the first set. Simona realized that as well and was determined to keep the rallies longer. That's clay-court tennis, it's why it's so difficult to win this tournament. Mentally you have to be tough, physically you have to be strong; you need a little bit of luck."
Down 2-0 in the second set, Halep also began to throw in a few higher balls, changing the pace, trying to get Stephens out of her comfort zone.
"I think she gave some great shape to the forehand today and was able to push Sloane back a little bit," Cahill said. "Then you can open up some court from there, but you've got to be patient, you've got to hit your spots. If you leave the ball short, you're in trouble. Sloane was hurting Simona in the first set. So Simona had to keep slightly better depth, little more patience and try to get to the legs of Sloane, and in the end she was able to do that."
Halep also became more aggressive. In the first set, as Stephens had dictated, Halep hit just four winners but made 10 unforced errors. In the second, she turned it round to nine winners and 11 unforced. In the third, as she ran away with the match, she hit five winners and made just five unforced.
Stats matter, but they rarely tell the whole story. Last year's setback no doubt helped Halep on Saturday. She handled the situation better and figured out those small adjustments -- even under pressure.
For that, she can call herself a first-time Grand Slam champion.