I’m a big fan of both Ratsmah and MaSsanSc, though Rats is probably my favorite arena player overall, getting him to explain his picks is a huge value to any new Arena players.
I highly recommend you watch and pay attention, even take notes if you want. I did:
Playing a 2/1 on turn 1, even against Mage/Rogue/Druid, is still a really good way to get initiative. Even if they ping it, that gives you a clear board for your 2 drop.
Grim Patron isn’t very good. Even with a Mage, it’s 3/2+3/3 for 5, but Mage doesn’t go for tempo early anyway. It gets it later, on turn 7, with flamestrike.
If priest isn’t on the board by turn 3 or 4, usually they have a hand full of removal and buffs that they can’t activate without things on the board. (The way they usually get on the board is with Dark Cultist.)
Rats doesn’t like to play too reactively; very aggressive for board control. Massan is the opposite: fully reactionary.
Consider your deck identity. Around 4:12 they’re choosing among Archmage, Rockbiter, and Forked Lightning. Rats suggests Lightning because of how aggressive arena is, and that increases the value of AoE removal. Massan also already has Kobold Geomancer and Azure Drake, which are both minions that improve spell power. This improves the value of Forked Lightning, devalues Archmage somewhat, and leaves Rockbiter as a purely neutral choice. However, Massan does already have a Rockbiter as this point as well, so that’s a point against it.
Rats hates Ancient Brewmaster, mostly because of it having 4 health. Too much can take it out right after it’s been played (it’s a 4 drop, meaning your opponent has either minions on board to trade up with it or has 5 mana to remove it some other way. 2 drop + ping.) Once of the worst 4 drops in the game, according to him.
Rats: “You’ll never be pissed about drawing into a taunt in the late game.” This is in reference to Elven Archer / AnnoyOTron/ Murloc Tidehunter. Massan originally wanted to go with Tidehunter, which I can kind of see, given his lack of early minions… but he’s only 11/30 through the draft. Seems risky.
Picking Forked Lightning over Lightning Bolt: keeps you from having to run face into a minion when clearing the enemy’s board, which is important when playing to not lose. Frost Shock not even considered here.
10:31 Rats: This is where I kind of give up on trying to make a 12-win deck and try to make a deck to get 7 or 8.
Rats says the deck is already really aggressive so go for broke and pure it up. It suggests he has a very flexible play style (you’d know this already if you watched his streams) while Massan admits he plays one way and tries to make his deck fit that.
Amani Berserker prevents Holy Nova/Consecration; keep in mind for aggro decks, so you can safely flood the board early against Priest/Paladin.
I’m not going to reproduce the entire explanation, but at 19:00 Rats explains a really effective trade.