This is something that’s become more prominent in football recently, with the emerging popularity of run-ups with hops and sudden changes of pace. Though some players have taken criticism for their run-ups, there’s a tactical reason for why they abruptly stop as much as they do: they can bait the goalkeeper into revealing which side they’re going to react to early.
For example, a fast, wide run-up likely means a shot to the opposite side of the player’s run-up (left run-up could mean a shot to the player’s right side, and vice-versa.) This is because it’s difficult for the player to twist their hips and place a shot accurately on the same side as their approach if they’re attacking the ball with a lot of speed from a wide angle.
Similarly, if a taker approaches the shot from narrower angle, they might be more likely to shoot the ball across their body, as that is the natural flow of the foot — it takes more effort to open ones hips up and shoot the opposite side of the run-up as opposed to swinging one’s foot across their bodies.
The pace of a taker’s run-up could also hold some clues for goalkeepers. If a player attacks the penalty with pace, the shot is likely going to have a lot of power behind it and will probably be airborne. So in this case, a goalkeeper may get into a diving motion slightly earlier in order to give themselves a better chance at stopping a high shot.
On the other hand, if a player is approaching the ball slowly there may be a lack of pace in the shot, so a goalkeeper will want to stay upright a little longer in order to get a better read on the run-up and where they plan on putting the ball. Staying upright in a balanced shape also avoids giving any clues as to where they are planning to dive.
