The world number one captured her fourth French Open title in June but has since been upset in the third round of Wimbledon, settled for bronze at the Paris Games and thrashed by rival Aryna Sabalenka in Cincinnati on Sunday.
But the Pole, known for her pinpoint serving, speedy defence and perfectionist approach to the game, will arrive at Flushing Meadows with a well-thought-out plan on how to get back to the winners' circle, 18-time Grand Slam champion Evert said.
"Iga's very disciplined, very organised, very serious about her game and very mature," former world number one Evert, now a tennis analyst for ESPN, told reporters.
"I see that she's going to be all business."
The tight team around Swiatek know when to push her and when to let her rest as they prepare for yet another change of surface, this time from the Parisian clay to the hard courts of New York, she added.
"She has a whole week ahead of her now to rest. I think she'll be fine," said Evert.
"When I say I think she'll be fine, I think she'll be fine in the second week, fine into the semi-finals or whatever. I can't say who is going to win with any kind of conviction at this point."
Swiatek took top spot in the world rankings following the surprising retirement of Australia's Ash Barty in early 2022 and quickly proved she belonged there, going on a 37-match winning streak and gunning her way to the US Open title that year.
She lost her top-ranked status with a fourth-round defeat at Flushing Meadows last season but bounced back to win the WTA Finals and reclaim the number-one spot.
The five-time Grand Slam champion has now been ranked world number one for 117 weeks overall and can tie Barty for seventh place on the all-time list if she remains there for the next four weeks.
Her main threats in New York appear to be the in-form Sabalenka, big-serving Elena Rybakina and defending champion Coco Gauff but such is the depth in the women's game that lower-ranked or even unseeded players could get their big break under the lights in Queens, Evert said.
"The women's side is very open," she said.
"The depth is more and more each year. Every first-round match, you must have your A game."