He can't do that. Most shot blockers in the NBA can jump extremely quick and if he jumps up immediately, he would have a high chance of getting his shot blocked. When you watch videos of him and even in the first 2 games, he always gets the big man to bite on the pump fake and then goes up. This gives him much more space.
Jalens turn around jumpers are so upright that the defender closes too easily. Gotta get stronger to fade away
I really don't like Lamb's game. Unless we're planning to tank this season, there's no reason he should be on a two-way contract.