I don't think the Graves nerfs are going to solve the main problem.
So Graves is getting the MR removed from True Grit. That's a step in the right direction, and will certainly make him more squishy, but I don't think it solves the whole problem.
Before I go any further,I'd like to point out that while I do play Graves sometimes, I'm not the best Graves NA, and I'm probably wrong about some of what I'm about to say. Feel free to correct me.
As I see it, Graves is basically an assassin. No CC, lots of frontloaded damage, high mobility. But he's also rewarded for sticking into extended fights. This, combined with his Black Cleaver synergy, makes him good at dueling as well, which isn't inherently flawed, it's basically the entire idea of Bruisers/Divers. But he's also ranged, and has abilities and basic attacks with AoE, so he can also teamfight well. Additionally, his safe and fast first clear means he's strong early game, but he also scales up extremely well.
So he's strong early, mid, and late, and can teamfight well, duel well, and assassinate well. Something has to go, and something is going, he'll now need to actually build MR or else die to mages, but in my opinion, that's not enough, not least because he can just build one of the 1800(read: 3) ADC items that give MR. I think they should just get rid of True Grit entirely.
This would primarily impact his early clear and his dueling, making him far less general a pick. I'm not saying it alone would balance him, it would probably bring him down to Azir-in-SoloQ tier, and if they were to do this, he would also need compensation buffs, or some different effect on his E, like bonus attack speed until his next reload or something, but I think it would make him more balanceable overall.
But of course, I might be entirely wrong. Maybe the MR removal will be enough. Maybe it won't. This is just a thing to consider and tell me I'm an idiot for writing.
.