Hey Neph; what makes these trainees so powerful? There ability to effect inanimate objects, lmao. Because neither of them has any worthwile feats against actual Force sensitive, only rock hurling and TIE destroying. Good thing Starkiller feats blow that out of the water by a drastic degree, and so does his accolades. And Vader was able to consistently TK him while arguably holding back, before become "far more formidable combatant" and further increasing his power again in RotJ.
Also, 'Killer utterly demolishing Galen clones that shared the same attributes Marek had to a lesser, or greater extent, shows he can indeed use that power on strong Force sensitives kek.