There exists an arena assist application called Arena Value. Basically, using image capture and recognition, the application reads each three card selection from the Hearthstone window and gives you a numerical rating of each card. Higher ratings are considered superior picks for an arena deck. The application programmer has a thread on the Hearthpwn forums, but it still seems a bit of a mystery how these ratings are computed. From the little that the creator has said, it seems to be an amalgamation of arena card lists from various arena experts (such as Hafu, Trump, Kripparrian, and others). Whether the program takes into account things like mana curve, existing card synergies, etc. is not well-known. That the application isn't open-source will keep the rating algorithm a secret for now.
The preamble out of the way, I was curious "How would the Arena Value application's picks differ from an expert arena player?" I chose Kripparrian for this experiment.
(Be sure to click the images for larger, more readable versions of the deck lists and choices. The bold minions are Kripp's choices. The numbers are Arena Value's card ratings.)
Kripparrian chose differently than Arena Value's recommendations eight times. The most interesting choices were on rounds 17, 22, 23, and 24.
At around pick 16 Kripp did mention that he was short of early draw, and that he needed more 2 mana minions to even out his mana curve. Pick 17, Novice Engineer over Stormwind Champion and Silvermoon Guardian would seem to play into that concern, as well as giving him added card draw. Pick 22 also seems to be a concern over his lack of early game draw; the Innervate gives him potential access to stronger cards in the early game.
Now, the Moonfire at pick 23 is the curious choice. He chose that card over Raid Leader and Silverback Patriarch. His early game was still weak at this point, and Moonfire without +spell damage cards isn't a very good choice in my opinion, and he only had a single Azure Drake. I probably would have chosen Raid Leader, simply because it's a 3 mana drop with minion buff. Watching Kripp's matches, I don't recall Moonfire ever giving him much value. On the other hand, I'm not a self-sustaining/infinite arena player (7+ wins consistently), I'm only a break-even player (4+ wins consistently), so I can't legitimately question Kripp's choices.
The choice of Wild Growth on pick 24 was likely because he felt he was weak in card draw. Yes, he had two Ancient of Lore minions at that point (plus a Novice Engineer), but that's a card that can give card draw or health, so depending on the state of the game when playing the Ancient he might have to forgo card draw.
(One note on this particular arena run. Kripp may have been able to do better, but his last match at 9-2 bugged out, and he was unable to make any plays. He finished 9-3, but he had a good shot at doing better.)
Kripp stated that it is difficult as Hunter to protect minions on the board, so to offset that he chose Sunfury Protector. With most other classes, Demolisher would have been his card of choice.
On his second pick he wonders if he should create a serious deck by choosing Acidic Swamp Ooze, or take a chance trying his luck with beast synergy. He decides for beasts and chooses Starving Buzzard. One problem he confesses about arena beast decks are a lack of solid mid-game plays.
Committing himself to beast synergy, Kripparrian chose against Arena Value ten times. Not much to say about those picks, since he generally chose in favour of beast synergy each and every time.
5-3 is certainly not the type of result expected from Kripparrian, but weak deck is weak deck even in the hands of an expert player. He likely did better than most players given the deck, but certainly not the 7-3 (and more) that Kripp usually pulls from an arena run. Would he have fared better had he chosen more in line with Arena Value? Perhaps. Probably. It is obviously hard to know for sure, but it is a general consensus that Hunter is a weak arena class to begin with.
Unlike Hunter, Kripp took this run seriously during picks. He wasn't going to rely on chance to give him particular synergies. He did end up taking two Sprint spells, which he stated was an uncharacteristic choice, but felt his mid-game was so weak that he would need the card draw late game.
Kripp made ten picks that weren't the "best" picks as per Arena Value's rating system. Granted, about five of those picks were toss-ups, the best and second-best picks only having a rating difference of a couple points.
The only interesting pick was Alarm-o-Bot, but considering his other two choices were murlocs, it made sense. Alarm-o-Bot was inconsequential in every match until Kripp's potential 12-0 match, in which the bot cost him the game.
At 8-0, Kripp did express surprise that this deck was doing so well. He expected 7 or 8 wins, tops. Patient Assassin was the unexpected star of the deck.
This was an interesting exercise. While Arena Value can help with card choice, it is still nothing but a tool, not an answer. The player still has to know their cards and what choices will add value to what they've already picked. And then they have to play those choices effectively.
Is Arena Value overpowered? Not in my opinion. Whereas it can't be said for sure that Arena Value's ratings would result in worse decks, I'd like to think that skill and experience count above and beyond a simple algorithm. I'd like to think that where Kripp differed from the application, that he was building the stronger deck. That said, Arena Value is certainly a valuable tool for inexperienced arena players and those looking to improve their arena deck building skills.
I may well do this again for arena streamers such as Hafu and Trump.