Her burnout was nerfed pretty good and reworked so that it was more powerful against jungle camps about a year ago but less powerful against champions. Her high clear speeds allow her to actually build devourer while still being strong enough to pressure lanes so she is the ultimate powerfarmer. She has a tough time against top laners with life steal/regen build into their kits (renekton, nasus, darius, garen, etc.) unless you trade a lot early to minimize that advantage. Plus some of the other top laners like Darius and Fiora have become somewhat of a nightmare to play against so some of the mediocre top laners look even weaker in comparison. I honestly don't think you could buff her to be comparable to the top laners (as it would make jungle shyvana broken) and find it more likely that they will just continually be nerfed over the next year or so until they reach her current state. Or an item comes along like red smite that allows her to go back and forth between lane and jungle to outfarm the opponent.