Baseball isn't a sport where you can draw meaningful general conclusions about any specific thing that you observe. With a player as anomalous and as talented as Cruz, this is magnified, because he's easy to project onto given that there really is no blueprint for him. At most he seems like a faster version of Aaron Judge, who also plays a much different position.
So if you see him take a bad swing? You start saying that he has bad plate discipline. And on and on. People just need to chill out. His callup has been overdue because he needs to be challenged by better pitchers than guys like Jerad Eickhoff. He's making the plays in the field and has also held his own at the plate, generally seeing a lot of pitches and making fine swing decisions. Today a decent lefty has gotten him to chase the slider for Ks, but that's a likely outcome that he needs to work through as he settles into everyday playing time at this level.
I do not think it is possible to understate how important he is for the immediate success of the team. Yes, baseball is a team sport, but Cruz is basically the main impact talent that we have, and so him hitting some of his upper ring outcomes is crucial for how quickly we can get the playoff window open.