Darius needs help Riots
He's sitting at 46% win rate. You can't ignore that. Few nerfs in a row made him quite depending on Fervor of Battle -> Remove Fervor -> Losing tank/tanky match ups -> Being without his special niche role (Juggernaut anti-tank). Yep we have an option with Phase Rush. But here comes the problem: What is the point of getting close to your opponent fast if you can't kill him? We lost significant amount of damage on our R with 9 bonus AD being removed without any compensation given and Fervor. I also want to mention AS Quints that also had to go. Yeah there is an option in precision tree (Stacking one). But stacking doesn't make Darius lane phase any better. (As I understand his concept he's all about laning phase and then quite situational teamfighting while being fed/having lead). For some reason this new runes system makes us chose between % attack speed and flat bonus damage. Sadly you can't have both and this is crucial.
So what can be done about our dunkman? I guess the answer is quite simple. Return his old Q width. So at least we'd have chance to stay alive then if we don't get to have strong all in damage anymore. If not that then bring back Fervor of Battle or make Press the Attack working with the true damage. That could be really helpful.
Better don't do that. xD