Enzo Maresca has said making the right decisions in the final third has been a problem for Mykhailo Mudryk since he joined Chelsea last year but the club are working with the winger to improve his consistency.
Chelsea beat Swiss side Servette 2-0 at home in the first leg of their Conference League playoff on Thursday, with the players still trying to adjust to new manager Maresca's system.
Christopher Nkunku scored the opener from the penalty spot in the 50th minute before substitute Noni Madueke made it 2-0 with less than 15 minutes left.
Mudryk has struggled to justify his huge price tag since joining Chelsea from Ukraine's Shakhtar Donetsk in January last year, and Thursday's match was one of the few times he has played the full 90 minutes.
Chelsea paid an initial €70 million ($77 million) for the 23-year-old with another €30m in add-ons.
"I think this is Mudryk, in terms of not only tonight, but in terms of since he joined the club. I think he had some good moments and then some moments like flipping a coin," Maresca told reporters after the match.
"You don't know if it's one thing or the other thing. If he can become more consistent, he can take one step forward. We are going to try and help him change.
"When he is in the last third it is about taking the right decision. For me, most of the mistakes from Misha is not about the quality or the technical mistake, it's about the choice."
Transfer speculation continues to swirl around Chelsea as Maresca looks to trim his squad, but one player he wants to keep is winger Madueke.
"I really like Noni," he said. "The only problem with him probably is that he has to understand he needs to be consistent during the week; every training, every training, every training."
Asked if he wanted the 22-year-old to stay at the club, Maresca replied: "Absolutely."
In a news conference on Friday, Maresca added that Chelsea will not shy away from bringing in a new number nine before the transfer window deadline if the player improves their squad,
"I just communicate the players that I like and the players I don't like. Hopefully, we can find solutions for them because at the end, when you find solutions, everyone is happy," he said.
"We don't need to sign players just for signing players. If we sign a player to make us improve, we will sign players, otherwise we are happy with the way we are. "If we have a chance to bring a number nine that makes us better, we are going to try."
Chelsea visit Wolves in the Premier League on Sunday.