KDB prime at Chelsea was not yet fully apparent, so he was not considered more than an ordinary player there. However in the hands of the right coach, KDB abilities could be brought out, and that was one of the reasons why KDB performance at Chelsea was not appreciated at all. There was nothing wrong with that situation, because it was simply a matter of the coach's ability to utilize a player's hidden abilities.
During his time at Chelsea, KDB didn't make a significant impact on the club, leading to his sale to Manchester City. Under Pep Guardiola, KDB achieved the best of his career, winning several titles with his teammates. Coaches play a crucial role in a player's development, as many players sometimes lose their best skills under incompetent coaches. In the Premier League itself, there are many examples of player quality, some with good initial skills but ultimately deteriorating because the coach failed to recognize their individual abilities.
The same thing happened to Palmer at Manchester City. He was considered unable to meet Pep Guardiola expectations, but now at Chelsea, Palmer plays a very important role. So, the compatibility between coach and player determines a player's fate. No matter how skilled a player is, it ultimately depends on the coach's expertise.
Now I'm curious about Gyokeres at Arsenal. Will Arteta be able to develop his talent as Gyokeres did at Sporting, or will we see a decline in his performance?