There's a lot of set up required to get a few draws from Battle Rage. To get good value you need to cut some armor gaining cards and you have to not armor up like crazy at the start. It can lead into survivability issues later on.
The card is fine. It actually makes the combo viable and even then you need to run a bunch of other draws to ensure you draw the Berserkers/Commanders/Patrons like Acolyte, Slam, Loat Hoarders EVEN Gnomish Inventors. This is no where close to Miracle Rogue where you played one Gadgetan and then just spammed whatever spells you had... you are specifically putting in cards that just draw for the Grim Patron deck.
Grim Patron is way more balanced than the Combo Druid. Grim Patron shines when the board is full, Combo Druid can 20+ HP off of no board with about the same or less amount of cards. That's why Combo Druid gets away with running far less draws than Grim Patron.
People just aren't used to Grim Patron. Soon they will realize that Handlock crushes Patron and so does Ramp Druid IMO. With only two Executes as your removal and no mid game/late game minion to challenge big taunt walls your combos will be rendered useless.
As odd as it sounds, meta will slow down with the existence of Grim Patron and Zoolock. You will see more Handlocks, Ramp Druids and Lightbomb Priests and less of Mech Mage, Face Hunter and Midranged decks. Hell people will even realize that Control Warrior is good again due to Grim Patron.
Of course this is at high level tournament play, on Ladders you will still see Face Hunters, Midrange Hunters, Mech Mage etc Because they are cheap and fast which results in quicker rank ups.