I think people hit the nail on the head here. Crosby just hasn't been able to penetrate the big 4. Hey, who can? But he is potentially the next best guy at #5.
It started out where we weren't sure in the beginning of his career. He had a 102 and 120 point season. Gretzky had 137 and 164. Adjust for the scoring and you still give Gretzky the edge. And then his 3rd season he broke every record in the book and just skyrocketed from there. So Crosby wasn't ever going to be another Gretzky. However, the first two years he was similar to Mario's first two. Mario had a 100 and 141 point year. That's similar to Crosby. Mario's 3rd year was good too, but Crosby made the Cup final his 3rd year. It was Mario's 4th year of 168 points where he hit a different stride and Crosby just never caught up. By season 5 Mario had 199 points and he was in another galaxy as Crosby who had 109 points in his 5th year. So we realized that Crosby just wasn't going to hit Mario's impact overall either.
Hey, nothing wrong with this. Who the heck can? Crosby did have those moments like in 2011 where it looked like he was going to lap the field and in 2013 too where he almost led the NHL in points despite missing 25% of the season. Similar to Jagr in 2000 for example. But to have him parallel with Mario or Gretzky just wasn't realistic anymore. Ditto for Orr. Orr had years that were bigger than Crosby's. The funny thing is Howe is probably the one Crosby is closest to in career value. Both of them play(ed) forever and are still good in their old age. Howe probably brought a bit more to the table overall with his physicality, but Crosby has done things that Howe has done as well when it comes to longevity. The only issue I think is that Howe at his best tops Crosby at his best. So yeah, I can't put him in the top 4 if I am being honest and I love the guy.
You can say with a straight face he is #5 though. Beliveau, Hull, Richard and Jagr are the forwards that all could make a case for it. Harvey and Bourque perhaps as defensemen. But you know, I think Crosby wins here. If you want to put any of the other forwards ahead of him that isn't a crime either, I get it, but he's had 8 times as either a 1st or 2nd all-star at centre, and I think he had a deeper elite crop in his era than Beliveau. Was he better than Beliveau? Different styles for sure and I think you can't go wrong building your team around either one of them, but he certainly merits being #5 all-time.
McDavid could very well be the #5 here someday. But let's not act as if 19 years of Crosby is worse than 9 years of McDavid. McDavid has been better than Crosby at his best, I think, but Sid had a better all around game and he took his teams a lot further and did it often. Few players have Crosby's playoff resume. So give McDavid time but he's not there yet.