Anyone saying McGroarty has looked bad for the Penguins is talking out of their ass. McGroarty looks good for the Penguins, just not "he needs to be in the NHL immediately" good. McGroarty will likely get half a season or so in the AHL and then jump to Crosby's line. He can absolutely be a 3rd line player in the NHL right now, but playing 1st line minutes in the AHL with top AHL scorers (which is what guys like Puljujarvi and Bemstrom are) is better for his development than getting 3rd line minutes in the NHL in defensive assignments. If Sullivan was willing to use his 3rd line in a more two-way or offensive role, I'd be much more inclined to put McGroarty in there. But with how Sullivan uses his bottom-6, him spending half a year in the AHL then jumping directly to Crosby's line is a better idea.
McGroarty's super high hockey IQ is his best trait from what I've seen, he simply knows where to be on the ice and anticipates plays really well. It's a very similar thing that made Guentzel a terrific winger for Crosby, I think McGroarty's upside is a more physical/bigger Guentzel. His skating is definitely really awkward, but I haven't noticed it as being a deterrent from the games I've seen. Granted, it's a lot easier to cover up poor skating if you have a high hockey IQ and know where to go. But the important part is that I think McGroarty's skating won't end up killing him as a prospect.
Great for Yager if he's doing well for the Jets as well, I liked him as a prospect although I've been unsure if he'll stick at center in the pros.