I also think Jagr is under rated by many and have no problem putting him and Crosby on the same tier but Crosby is definitely higher and has an entire career of prime play from the drop and it took Jagr until his 3rd year to reach elite level.
That creates separation between the 2 as well as playoff resumes.
Jagr isn’t as bad in the playoffs that some of his detractors would have him but Crosby in in elite territory playoff wise as well.
Sure, it took Jagr longer to get going (although he already led the playoffs in even strength goals & points at age 20, during the Pens' second Cup), but also won a Pearson at age 34 while playing with castoffs and had more points that year than Crosby did the following year (in what was easily his career high season in points).
Crosby's been good in the playoffs, very good thru 2009 ECF, not as good after that IMO. From 2009 SCF to present (ages 21-33): 132-46-85-131 (-3)
He and Malkin have also benefitted from relatively easy roads in the playoffs. The one time they played Boston, they were skunked and swept. They did get past a strong Lightning team, although they were each < PPG. Of all the post-lockout western powers, they never had to play Chicago or Kings, but did play Wings twice. They were fortunate to get some help from league before series (moving it up a week when Datsyuk & Lidstrom were gimpy) and from refs in game 3 (missing blatant too many men that helped Pens stay in game and eventually win), but hey they did split the two SCF with Detroit... thanks Max Talbot! Crosby was 13-2-6-9 (-2) to go along with his 4-0-0-0 (-2) vs. Boston in 2013 ECF. Malkin was 13-3-8-11 (-2) to go along with his 4-0-0-0 (-5) vs. Boston. So when they had to play tough defensive teams (although 2009 Wings were actually not super tough, based on regular season GA and those injuries to key defenders), they didn't fare very well.
Against teams in the upper half of defense among playoff teams (either top 4 in conference or top 8 in NHL in GA among those teams), Crosby has 0.80 PPG in 82 GP, while Malkin has 0.89 in 81 GP. This contrasts to other players in such circumstances, such as:
Peter Stastny 1.28 PPG in 74 thru age 35 (higher scoring era... but he also faced top 4 in NHL GA in 12/16 series)
Jagr 1.23 in 96 from ages 20-36 (average defensive opponents overall)
Bure 1.22 in 46 (somewhat easy)
Kucherov 1.17 in 75 (pretty tough)
Sakic 1.05 in 146 (somewhat tough)
Forsberg 1.05 in 127 (somewhat tough)
Kane 0.99 in 96 (pretty easy)
Who's in Crosby's range? Iginla at 0.80, Thornton at 0.79 & Stamkos at 0.78 (Iginla & Stamkos faced tough defensive teams in playoffs, Thornton about average).
Sakic & Forsberg's median playoff opponent ranked 3.0/3.5 in conference and 5.0 overall in GA among playoff teams. Crosby & Malkin's median playoff opponent ranked 5.0 in conference and 10.0 overall in GA among playoff teams. Using an average weighted by GP, Sakic & Forsberg had opponents averaging 3.5 in conference & 6.3 overall, while Crosby & Malkin had opponents averaging 4.3 in conference and 8.6/8.7 overall. Sakic & Forsberg played teams in the upper half defensively among playoff teams 25 & 21 times respectively, while each had 5 series against teams in the lower half. Crosby & Malkin played teams in the upper half 15 times and in the lower half 16 times. So those numbers, their PPGs against opponents in the upper half, and specific series against the defensive powers tell the same story: Crosby & Malkin had it quite easy relative to most others, which boosted their playoff PPG. I'm not saying they haven't beeng good, of course, but they haven't been nearly as great as many perceive.