A little while back Blizzard added "synergy picks" to Arena in order to allow for more combo-centric decks, especially for dragons, elementals, and other tribal cards. Unfortunately, the newly added system did not work out as planned. You are guaranteed to get synergy cards such as Auctioneer and Book Wyrm in your first few picks, but all of the following cards are chosen entirely at random, so even if you planned to make a dragon deck there was no real guarantee you would get any more dragons.

The end result was that each and every single arena deck featured the same few cards, usually without any sort of activator to make them actually useful. As you might imagine, having basically useless cards clogging up decks did not go over well with the general Arena playerbase, which then quickly turned on the new "synergy picks" system. Thankfully, it would appear that Blizzard is aware of the problems and are looking to address them in the near future.

According to Mike Donais the removal of the "synergy picks" will not arrive as a part of the upcoming balance patch, but rather the patch after that. So while I would love to tell you how long you'll have to wait for Arena to become a bit more interesting, I'm afraid I'm just as much in the dark as you are. On the positive side, at least we know that the changes are coming, but until they finally arrive you might want to sneak in a couple of prayers to RNGsus, just in case.