Point-wise, we're clearly getting a good return on the financial investment.
His play at ES has been decidedly sub-par, but I wasn't really expecting much there, so I'm honestly not that disappointed. He needs to be better away from the puck and while managing the puck. He could stand to be a bit more noticeable as a physical presence as well, since that's one of his biggest selling points. He isn't shy about sticking up for himself or others, and that's always a welcome trait in any teammate.
I don't know if the Blues decided to emphasize play lower in the zone on the PP specifically because they now have Maroon, a notion I kind of find hilarious if I'm being honest, or if Maroon is just the current beneficiary of a shift in philosophy that was long overdue in coming. Either way, the PP is working and that's not a bad thing. I don't think Maroon's talents have much to do with it himself, but he isn't preventing it from succeeding, and there's something to be said for that.
Overall, I'd give his early work a C grade. As the season goes on, that grade is going to depend more and more on how he's playing at ES. We should have plenty of other options on the PP (Fabbri now, and perhaps eventually Thomas/Kyrou), so Maroon's performance there shouldn't be critical one way or the other . There's no hiding from bad play at ES, though, and that's going to matter as long as he's skating in the top 9.