It's no secret to any experienced "Hearthstone" player that the game's Arena mode is still pretty unbalanced. The game format, which involves drafting cards from batches of three for 30 rounds until you end up with a full deck, favors certain hero classes due to inherent card design. If you want sure wins, there were some classes that you just had to pick.
Which is why it came as a surprise to find out that "Hearthstone" developers Blizzard Entertainment were planning to remove a bunch of cards across all sets from the format. This will be done in order to balance the classes across the board and enable some underpicked classes, such as Warrior, to get more play in the format. According to Blizzard, they've been experimenting with these changes ever since they kept C'Thun cards out of the mode in the release of "Whispers of the Old Gods."
On viewing the full list, however, it still seems as though the powerful classes in the mode didn't get a lot of changes. Paladin, still one of the strongest Arena classes in "Hearthstone," isn't getting any cuts. Mage is losing Snowchugger, Forgotten Torch, and Faceless Summoner, while Rogue is only losing Goblin Auto-Barber and Undercity Valiant, all of them cards which can be easily played around in the game, except perhaps for Forgotten Torch. Looking at the whole list, it seems as though the changes made were completely arbitrary.
Blizzard is really going to have to find a way to make some real fixes to "Hearthstone"'s Arena mode, but banning is the right step. It's certainly better than issuing errata for cards already out there. If you want to see the full list of cards Blizzard removed in Arena mode, you can check it out over on Polygon, who put the whole list together.