The discrepancy is the game calculates whether the E was successful or not at the time of cast, not at the time the E connects ~0.25 seconds later. An excellent example of this is in Dunkey's 'Slam Dunkey' Video. An hourglassing fiddles flashes out of E as Dunkey STARTS the cast.
Watch this at 1:07, slow the speed down to 0.25x and you can clearly see what I'm talking about.
https://www.youtube.com/watch?v=m2ONLDKum38
Fiddles is CLEARLY out of range by the time the axe LOOKS like it grabs, but since the grab is decided before the animation even finishes, too bad, so sad.
Fiddles gets pulled across lane 1400 units.
If Riot won't change the pull metric to detect .12 seconds later they could at least adjust the tooltip.