The long and short of fairway metals
This is the 90-degree angle that must be restored to straight by impact. At this point, the radius of the swing has changed due to his cocked wrists, and power is stored in his “short” left arm.
At impact, the full radius has been restored, and the left arm is long again, releasing pent-up power.
Fairway metals, such as your 3-metal, are often the most difficult clubs in the bag to hit effectively because they have the worst of both worlds - large metal heads and not much loft. This dangerous duality leads to a visual image on your mental screen that says, "I can't get under the ball with this low-lofted, big-headed club."
This leads to all sorts of swing mistakes, but the two most common are: hitting behind the ball and then hitting thin and topped shots.
Of course, the idea of getting under the ball is a common misconception. Your goal is not to get under the ball, but to cleanly hit the back of the ball with a downward blow. The good news is that both the fat and thin misses can be corrected by proper restoration of your swing radius.
The radius of your swing is the straight-line distance from your left shoulder to the clubhead. If you start with, say, an 80-inch radius at address, you should finish with 80 inches at impact, otherwise you can't make solid contact with the ball.
During your swing, this radius is "lost" as the wrist cock creates a 90-degree angle between the lead arm and the shaft of your golf club. Once this happens, the goal is to restore the radius in time for impact.
In the correct swing, the radius is at its longest at both address and impact. If you're topping or catching your fairway woods and metals thin, you're returning to impact with a "short" left arm. Good fairway metal players have a long left arm at impact, meaning that the club is a straight-line extension of the arm.
This drill will give you the feel of the long left arm: Start your swing from the impact position shown in the second photo below. Begin your backswing by replanting your right heel on the ground so you'll rebound onto your right side. Let momentum guide you to the top of the backswing, then continue your swing to the finish.
This will give you the feel of restoring the radius and shallow out the shape of your swing arc - a must for fairway metals. Think "long arm to short arm to long arm."