Overhead Position - Avoid Excessive Forward Lean
In the overhead position, we want the trunk leaned forward to allow the optimal structure to support and stabilize the weight.
This allows us to create a strong base with the shoulder blades against the ribs, and hold the arms vertically with the bar above the base of the neck.
When you lean past this degree, you begin compromising the structure rather than improving it.
Excessive forward lean means likely shifting your balance forward, but also forces the bar to move backward to counterbalance the body, meaning instead of both the force and structure being vertical and easy to support and stabilize, you now have the arms leaning back in a weak position.
The position itself is important, but so is your timing trying to create it. Leaning too early in the lift will move the rest of your body backward in reaction—in the snatch that means the feet jumping backward out from under the bar and the hips sitting back, and in the jerk, it means over-reaching the back foot, landing short with the front foot, and the hips being behind the bar.
The result in both cases is the bar being too far forward relative to the body, which at best means a difficult recovery, and at worst a complete miss.
Let the forward lean of the trunk happen in reaction to your attempt to pull/push the bar back into place overhead. This will help ensure both that the lean isn’t excessive, and also that it begins at the proper time—after the feet have reconnected with the floor, meaning that leaning motion can no longer negatively affect their position.