I would suggest you are looking in the wrong direction if the distance is further than expected. "Forward" is "towards the target"; "back" is "away from the target".
Normally one would say the spot has been placed back from its expected position, and needs to be moved forward towards the target:
Why is this spot so far back from its normal position? It needs to be taken forward 50m.
Even if it's the batsman asking, he would still use forward and back to explain the relationship to the target, but the verb would change to indicate the motion towards him (and this would change to that of course).
Why is that spot so far back from its normal position? It needs to be brought forward 50m.
Having got that out of the way, it's possible to address ahead and forward. Let's say the pitching spot is at 50m instead of 100m. Either word will do, but forward seems more natural. Ahead indicates a separation from the speaker and the point in question; someone standing at the right place and peering at the marked spot in the distance might use ahead.
Why is the spot so far forward of the right place?
Why is the spot so far ahead of where it should be?