example, like leblanc. from her stats, it isn't terrible (or so I would assume), but I notice that in a teamfight she might not be able to pick off a target. is this right?
but I also need a definition on what makes it so that they "fall off" like renekton or lulu. or is it purley that they cant deal very much damage?
hater free zone3 votesFalling off just means that as the game progresses, their scaling becomes less and less significant. In the early game, 20AP is much more significant than 20AP in the late game, by nature of how champions resistances increase as they level up. Champions resistances are a cumulative increase per level, where as damage is dependent on the raw stats of each item purchased. Champion's abilities often convert these raw stats into bonus damage by ratio of the that champions sum total of their bonus offensive stats, or their entire offensive stat.
While some champions may have a stronger offensive power in the early game, the ratios/percentage of their extra damage stat stays stagnate, meaning as the enemies defenses scale up, those damage stats become less meaningful since they aren't scaling to the same degree as the enemies defensive stats.
Gigglingdeath1 votesWell put, have my vote.
Rustling Bush1 votesi don't think theirs really a definition for falling off outside of "their kits just aren't as effective as others, late game", champions fall off for different reasons.
example: 
and 
both have similar playstles, you jump in stun someone then wail on them.
early game: passive to block autos, high bases (as well as critting always on low targets) and ability to instantly stun someone makes him downright oppressive in the laning phase. Late game his damage becomes sub par, his ability to stun one person isn't very useful and his passive makes little difference.
early game: does ok damage, doesn't have as reliable of a stun and easily punishable if he fucks up. late game his damage becomes insane cause of scaling, he can stun multiple people and his ult gives him free armor/mr making him hard to kill.
they both play similarly but are stronger at different points in the game usually because of scaling.
Quepha1 votesIt can have to do with their scalings, whether that's through ability points, ratios, base stats, or auto scaling, but it can also have to do with the way the champion's kit adapts to the pace of the game.
The Bearded Bard1 votesLeBlanc specifically falls off because she's a single target burst assassin that relies on engaging with her face and has to wait 1.5 seconds to do damage. Late game adc + support combo should be plenty to kill her before she can kill the adc.
