But Fabian Hurzeler says they are all showing the right work ethic to meet their new Premier League challenge.
Stefanos Tzimas, Charalampos Kostoulas and Tommy Watson are not expected to make debuts in the season-opener against Fulham.
Albion boss Hurzeler said: “They have to be patient. They are in their phase of adaptation.
“Some of the players adapt faster than other players regarding the intensity and the demands from the Premier League.
“But they all have the right work ethic, the right character sides to adapt quickly to this intensity, to the demands. So I’m quite convinced that we’ll see them soon.”
Kostoulas, known as Babis, was shown starting his first training session with the squad ahead of last Saturday’s friendly with Wolfsburg.
Hurzeler said: "Regarding Babis, of course, there's a big spotlight on him because we spent £30 million for him. That's a huge amount of money, but I think it's very important to understand where he comes from.
'He's coming from a different culture, a different league with different demands. And if you have talks with him, you can feel it, that he needs time to adapt to the intensity here.
"It's not only a different culture, it's also just a different adaptation for his body. So how much sprint distance he has to do here during training, how much high-speed distance he has to do during training, it's something completely different. And the body just needs time, especially when you are that young.
"You need time to adapt, not only physically, but also in some ways mentally. Therefore, we need to give him the time and we need to be very patient with him, because I can say that he won't be immediately in the starting XI. He also might not be playing tomorrow."