Suggestion of a new stat: Shield Penetration

As you guys know, lately we've seen a huge problem related to the ADC's being overpowered, wich is the amount of shields on League of Legends. Even tough the problem of the ADC's dealing Burst per Second instead of Damage per Second won't be fixed, my suggestion will certainly help against those 'stack shields on ADC' comps.

First off, I've been thinking about this subject because I'm a AD assassin player monstly (Ex. Zed, Talon) and I think it's just ridiculous how hard it is to me to kill the enemy ADC even if I hit my full combo. So like lethality I was thinking:

Could we make a stat that ignores % of the shields? For example, the enemie has 1000HP and a shield of 500HP. If you had 50% of 'shield penetration' and you dealt 500 damage the enemie would have 750HP and 250HP of shield (50% of the damage was dealt to the enemie's HP and the other 50% to the shield) . I would love to explain this better, but tbh english isn't my 'mother language' as you can probably guess, but I think you guys can get the idea with this example.

How to balance this stat? Well, I have no idea. I just think that's the Riot's job to do it, but I think it's certainly a good idea of stat that would be very appreciated on the Assasins and Divers class monstly, since the League of Shields and Stopwatchs took over the game.

What're your toughts? Feel free to share.