To add to that, the trajectory of his Chelsea career appears interesting.
He scored the winning goal in the CL final in his debut season, whilst having a manager who believed in him (Tuchel). So as a big money signing going into his second season, confidence-wise he ought to be in a good place all whilst playing in his optimal position behind Lukaku. Unfortunately, like his first season where he scores more goals as a CF, he doesn't really register statistically for most of the season (as an AM) until March when he scores 5 goals in 5 games whilst positioned as a striker. He ends the season scoring 10 goals as a CF across the PL & CL with a total of 14 goals in all competitions. Obviously, playing as a striker allowed him to score more goals, but the issue was more that he almost never scored as an AM.
Regardless, he improved (statistically) in his second season and there was no reason why that couldn't have continued trending upward. Additionally, the indicators all pointed towards him being far more effective as a CF rather than an AM, so a breakout season as a CF wouldn't have been a complete surprise. Fortunately, Chelsea were an absolute shit show and he played a key part in that.
What I find interesting and have observed so far at Arsenal is that he looks much better as a CF rather than in midfield, despite my initial thoughts being that he was played out of position. He looked far more likely to impact the game against City playing upfront, than he has done in the following three games in midfield combined. This aligns with the fact that statistically at Chelsea, he was much more effective as a CF where he was able to score goals and as he's not an assister, was completely ineffectual from midfield with barely any goals or assists.
