That I understand, except for when champions are buffed and nerfed without compensation. Say every champion has a power score (PS) of 10 (+/- 1). If one were to be buffed, then they would have a PS > 10 (+/- 1), and if nerfed, a PS < 10 (+/- 1). The exact number change would depend on if it was a tweak, massive buff, or a gutting. Though wouldn't designing/developing all champions around a close to equal PS automatically balance them? And wouldn't changing them with one-sided buffs/nerfs, destroy this inherent balance?
In terms of Lucian, he has a lot of strengths. Ranged Poke, Kiting ability, a Dash with a CD reducing mechanic, Wave clear, Burst, Minimal Cast Animations/Times, moderate to short CDs, Early Game kill pressure, multiple build paths, smooth mid-Late Game scaling, and a Trade-Winning passive. (might be more)
His 3 biggest weaknesses are that he is an ADC (so squishyness), his kit only has 1 pre-6 AD high scaling ability (post-6 only 1 high AD scaling ability until passive catches up), and Cooldowns.
Lucian never seems to have a "fall-off"/"Plateau" point (like Caitlyn for example) to justify his early game strength. He snowballs relentlessly when given the slightest advantage.
So I find it hard to say his other abilities are weak enough to justify his passive, especially with the recent buff to his cast times.