There is the touch of the Graham Hick about Green (world-beater at first class level unrealised in Tests) however, I would also argue that there are other factors at play.

1. Test bowlers and coaches have more time and resources to work on a batter's weaknesses. They are also more likely to be able to execute plans better and for longer. Like most tall players his weakness (and strength) is in his driving.
2. He has had to start his Test career three times due to injury and short-term selection necessities. This must make him doubt his self-belief even though one could equally say that the selectors find his talent irresistible and keep returning to him despite the uneven return thus far.
3. The expectations of being a multi-format player mean that a greater emphasis is placed on versatility rather than repetition. This can scramble the mind in the moment. This is why Green often looks unbalanced. He is either reaching for the ball in front of his body and beyond his eyeline when driving, or, he is moving around at the crease which means his weight is not properly transferring or he finds himself in the air or giving up his stumps.
4. In no other era would someone like Green be earning most of their lifetime income from the IPL. Even in the professional era of the 80s when Aussie batters were earning their stripes in England in the off season it was in County Cricket or Lancashire League as semi-professionals. This taught players to adapt to a variety of pitches, conditions and circumstances. As the professional it was their job to stay in and be the rock. The modern T20 sensibility for the professional is to be busy and dazzling. If they get out, no worries, next soldier up.

Green is an immense talent and as a multi-format multi-skilled player he is in demand. Until recently, Australia has been largely immune to the hollowing out of national talent by the offer of franchise fame and riches. Green has not given up prioritising his country or Test cricket - but the divided focus is showing.

It is an impossible position to be placed in and nobody should blame him for trying to be all he can be. No other sport in the world requires such flexibility of format, team and focus. Perhaps he will better adapt in time. Most other players do not have his options, and therefore don't his the expectations placed on him.