Is it 22 lands? Did I understand the algorithm correctly and did I draw the correct conclusions, or am I getting it wrong?
From what I have read, the arena algorithm takes 2 virtual copies of your deck, shuffles and draws a hand from each. It then picks the hand (and deck) with the ratio that is closest to the ratio in your deck. (maybe i already got that wrong?).
21-land-deck with ratio = 0.350 (21 / 60)
1-land-hand -> ratio = 0.143 -> distance to deck ratio = 0.21 2-land-hand -> ratio = 0.286 -> distance to deck ratio = 0.06 -> 2-land-hand gets picked :( 3-land-hand -> ratio = 0.429 -> distance to deck ratio = 0.08
22-land-deck with ratio = 0.367 (22 / 60)
2-land-hand -> ratio = 0.286 -> distance to deck ratio = 0.08 3-land-hand -> ratio = 0.429 -> distance to deck ratio = 0.06 -> 3-land-hand gets picked :) 4-land-hand -> ratio = 0.571 -> distance to deck ratio = 0.20
So as I understand it, in a 21-land-deck, if one of the 2 opening hands contains 2 lands, it will always get picked if the other hand has a different number of lands.
And in a 22-land-deck, it's always the 3-land-hand that wins.
So it's 22 lands?
I must say I changed back to 24 lands recently, because I was getting 2-land opening hands in what felt like more than 50% of the time, when it should have been closer to 30%. But I didn't actually record any numbers, so it might just be my perception.