There is no doubt guys like Mika, Panarin, Kreider, and Fox are at the top of the list for why the Rangers are trailing the Panthers, it is on those "top guys", agreed.
With that said, I disagree with you guys on Roslovic adding anything really, and I claim he is useless two reasons. First, 4 of his 8 points, and both of his goals came against the very overmatched and outclassed Caps. In the 11 games since he has zero goals and 4 total points, and only has points in 3 of 11 games, so 8 of the 11 games in rounds 2 & 3 he has zero points. Second, he was not brought in to be a role player, he was brought in as the RW upgrade we needed to play with Kreider and Zibanejad, and he has been terrible at it. Wennberg has 1 goal and 2 total points in the playoffs and is 44% on FO's. Wennberg is not useless because he is a responsible player who plays on the PK as well, but he is not adding a lot of value, and I feel he is a big reason the 3rd line has done sh*t all playoffs. Those are the two guys Drury added for our big SC push, and it was not good enough.
To your question Panzer of who Drury could have traded for, it is a very fair and legit question, and I don't have a for sure answer. All I will say is just because someone wasn't traded doesn't mean he couldn't have been for the right offer. If Drury was willing to trade the 30th pick, could we have gotten a legit RW. Could we have gotten Buch, could we have gotten Vatrano, could we have gotten someone else of value, maybe a C who could actually win a FO and score a few goals unlike Wennberg? Not sure, but I know what we did add was not good enough. But hey, the playoffs are not over yet, maybe one or both of these guys will step up and help us come back and win this series.