Quote from Iplaydecksnstuff »Why do you think that? is it just because gamble has the chance of discarding the chosen card and it isn't an instant? it just seems very useful, but I haven't tested the deck thoroughly enough to know yet.
Crop Rotation gives you the instant speed which is very important, especially when comboing out. The only upside to gamble is that you can go grab Life from the Loam and possibly Exploration/Crucible if you have enough cards in hand to risk it.
Crop Rotation also gives you game against other decks game 1 like Dredge/Oops all spells/Belcher/Past in Flames storm variants, etc.