De Vries has had a rough start to his F1 career, struggling to match team-mate Yuki Tsunoda in his first five F1 races after being signed to replace Pierre Gasly.
The 27-year-old Dutchman has suffered a spate of costly crashes while also failing to match the Japanese driver's pace both in qualifying and in races.
In Monaco De Vries reached Q2 for the second consecutive time as he cut the deficit to Tsunoda to less than two tenths.
On Sunday he put in a measured drive to 12th, re-gaining a place he lost to Valtteri Bottas when Tsunoda's brake issues dropped him down to 15th.
It followed a Miami Grand Prix weekend during which De Vries outqualified Tsunoda for the first time.
Red Bull's Marko said he was much more satisfied with how his latest signing performed on a tricky Monaco weekend.
"This was by far his best weekend for AlphaTauri," Marko told Autosport. "Nyck was much closer to Yuki than before. This is what I want to see from him.
"Yuki was also really good until the brake problems came again. This is something that has to be solved by the team, they have brake problems so often."
Still, De Vries is yet to get fully on par with Tsunoda, which remains Red Bull's expectation as it hoped his extensive experience in F2, Formula E and sportscars would help kickstart his learning process.
"Of course we want to see more," he added. "We thought we'd bring in someone with some experience already to challenge Yuki. But that didn’t happen yet, so that is the most important thing.
Marko refuted rumours that he had set a Spanish Grand Prix deadline for De Vries to show marked improvement before considering a replacement such as Red Bull junior Liam Lawson, whose star is rising in Japan's Super Formula.
"There is never a deadline. We just watch it and look at the performances," he replied when Autosport asked him to address the Barcelona rumours.
"When we have to act, then we will act. At the moment we don’t do anything."
Before the Monaco weekend De Vries, who has yet to score points in 2023, said it was "not a shock" for his seat to come under increased scrutiny.
"It's not a shock to me, it's normal; it's this industry," De Vries said. "It's always been like this in Red Bull and in Formula 1. I genuinely believe it's no different than earlier in the season.
"You've always got to perform, you've always got to deliver. It's been like that throughout my whole career.
"As a driver, you always fight for your survival, and you always need to deliver to continue your career forwards successfully. It's normal. It's how it's always been."
