It's hard for me to make any judgements based on MMR because last month+ pretty much all my games have been 5-stacks in Reborn, where until recently matchmaking has been a bit wonky. I've like 75% winrate for that time, enemies often seem to be way below us in MMR and half the time aren't even a 5-stack. We clown around and don't tryhard and still win. We played 3 times against some stack that was farming ~100% winrate accounts in Reborn and only lost one game to our awful picks after which those guys just started dodging us. But generally I've seen both of those Storms, the ones that gank after losing mid and the ones that farm. Usually the ones who last pick Storm are the ones who have some idea of what they're doing and know when to just farm, which makes them doubly annoying.
But again, the issue is that Storm can just capitalize on one or more weaker players/heroes in your team. You can know exactly how to deal with Storm but it won't always help when your teammates aren't on the same page. And even when you know how to deal with Storm he can still put a lot of pressure you, knowing you can't farm a lane alone anywhere on some heroes when an Orchid Storm is in the opposing team is more than mildly annoying.