He's broken according to what metric?
He's below the 50% winrate threshold in both Top lane and Jungle, and while he's still a contested pick in the Jungle, he's almost fallen entirely out of favour from the Top lane, placing 42 of 53 in overall play rate out of all champions picked there. In either of these scenarios, he also falls off quite hard late game. Finally people who dedicate the highest amount of time playing him (125+ games) have a winrate that is, again, below the 50% measure.
Graves is an early game bully, with a relatively powerful zone of influence at close range. That being said, he does not have a ton of mobility or utility, making his fit into different team comps heavily reliant on heavy utility picks either in the top lane or support role. Aka. he's hardly overwhelming without the appropriate setup to back him up.
After the recent nerfs in particular, and the upcoming assassin reworks, I suspect Graves will fall in popularity and viability.