You're Correct!

If you are going to play effective golf shots with your irons, you need to ensure that you have the correct ball position for the iron that you are playing.

Basically, you need to play your shorter irons from the middle of your stance and your longer irons more forward in your stance so towards your left foot, if you are a right handed golfer.

Your sand iron, pitching wedge and 9 iron should be played from the centre of your stance and then the golf ball should move half a ball forward, or to the left, for each subsequent club as the shaft gets longer. The reason for this is because the shorter the shaft of the golf club, the more upright you set the shaft at address. As you swing, you make a more upright or steeper swing with a shorter shafted club and this results in you swinging the club head down along the target line for longer. As such, the club face aims at the target by the centre of your stance and with the ball positioned in the centre of your stance, you will hit the ball at the target.

The longer the shaft of the golf club that you are using, the flatter you set the shaft at address and so the flatter your golf swing becomes. This results in you making a more arcing swing that results in the club head not travelling along the target line for as long and so it takes longer for the club face to square, or aim at the target, hence the longer the club becomes, the further down the target line the ball is positioned.

If you play every iron from the centre of your stance then you will find that as the club gets longer, you start to hit the ball to the right of the target. With your shorter shafted irons, sand and pitching wedge and 9 iron, you will strike the ball at the target with a centred ball position. However, as the shaft of the club gets longer, you swing it on a flatter plane and therefore the ball needs to move further down the target line in order to allow you to square the club face at the target. If you play your longer irons from the centre of your stance, you will hit the ball right of target as the club face will be aiming right of target when it impacts with the ball.

If you play all your irons from a ball position forward in your stance, you will hit your longer irons at the target, but you will hit your shorter irons left of target. This is because your shorter irons are swung on a more upright plane and so the club face aims at the target by the time the club head is being swung along the target line, in the centre of your stance. If you play a forward ball position with your shorter irons, by the time the club face strikes the ball in this forward position, the club face will be aiming left of target and the ball will miss the target on the left.

Playing your irons from a ball position back in your stance will give you issues with strike and trajectory. The club head will be on its down swing as it approaches the golf ball, however, if it is too far back in your stance the club head will strike the top of the golf ball as it swings on a downward arc. This will produce a very low golf shot that does not travel very far.