As it stands, Crosby has 200 playoff points. He is likely to overtake Jagr in the coming days at 201. That means the only ones ahead of him are Gretzky, Messier, Kurri and Anderson. All dynasty Oilers. Messier is 2nd at 295. Unlikely Crosby catches him, but does it mean he is a lesser playoff warrior? I think at the moment it does.
When did Messier have a poor playoff showing? Almost never. 1982 is the worst I've got where you can say he cost his team and they lost partially because of his performance (although all of the green Oilers blew it). He has his own Smythe and other Smythe-worthy runs. Captained two different teams to the Cup, won 6 of them overall and played in 7 Cup finals. Crosby likely won't surpass any of them. The other time Messier had a year that wasn't up to par may have been 1991, when he was hurt. But he is a rare breed where he produced well even in losses.
Crosby does have some postseasons that were lousy. Not many, but they are there. 2015, 2019, 2020 and 2021 come to mind from a statistical perspective. All first round losses. There are other times such as 2010 or 2013 where his stats look good but he faltered in the later rounds. 2012 where he was on the wrong end of a pond hockey series, in which he should have overtaken Philly with. There are times he's gotten thrown off his game, I can't remember Messier doing this, really.
He's also been good in all 4 Cup finals runs he reached. Not to mention some other times like 2018 where he looked very good. But there isn't quite that consistent string of good postseasons performances like Messier. If we are to nitpick a bit we have to give the edge to Messier for sure, even if Crosby has a wicked run to the final this year. There are just too many examples of Messier being a playoff warrior, that even the best playoff performer of our own generation right now is not quite there.