It was neutral jing, where "Neutral jing is the key to earthbending. It involves listening and waiting for the right moment to strike."
But that felt specific to Aang, the Airbender, not the Avatar.
Air and Earth are opposites to each other, in respects to both literally and bending disciplines. He needed someone who mastered the root of Earthbending. Bumi did, but he needed to stay in Omashu and "wait" for the Day of Black Sun to take back Omashu.> Korra had teachers handpicked and it's sort of implied that this sort of coddling fucked her up in a way
Not necessarily coddling, but she discovered she was the Avatar by herself and was able to bend 3 elements at age 4. It made her cocky, and she was better than her opponent in terms of winning fights and being stronger than her opponent. Air was the most spiritual and humble of the 4 elements and her cocky attitude was counter to that.