The bolded is flat out wrong. Coyle played 70 games this year and Krejci 61 games, that's a difference of 9 games. Coyle and DeBrusk played together for 311 minutes this year. So if DeBrusk ONLY plays with Coyle when Krejci is hurt, that means in those 9 games, Coyle and DeBrusk were playing on average 34 minutes a game together.
On the first PP, it was a rotation of players all year long. DeBrusk, Coyle, Heinen, Ritchie & Krejci (playoffs) all got looks on the first PP unit this season. For all the PP TOI the first unit got, DeBrusk was on the ice with them roughly 55% of the time.
I mean fit is part of the equation in everything. The team was looking for a goal scoring winger to play with Krejci, who is an elite playmaker. Danton Heinen (and I've been very vocal in my support of him) was not a guy fit that role. DeBrusk was drafted as a goal scoring winger, so why wouldn't he get put with your teams best playmaker?
Now with the points, there are a few corrections/observations here:
It wasn't 40pts, it was 43pts that DeBrusk had his rookie year. So with 7 less games, DeBrusk produced 4 less points and the same amount of goals. Not only that, but in average TOI, Heinen was higher than DeBrusk.