^That link takes you to posting a new message, not the article.
I tried the home page, and couldn't see anything there.
To try and answer the question - I'm not sure. Keepers can move along the line, but, supposedly, not off it, but the number of times a save is made when the keeper is 2 yards or so off his line is noticeable.
A number of years ago, I played a game on an artificial pitch in Newton Heath, and it surprised me, as a goalkeeper, after a lot of years not playing, how large the goal was.
I'm about 6 foot tall, and I laid on my side with a outstretched hand on the goal line, and there was still a gap to the post, so it made me think with a well placed shot how difficult it seemed to reach the ball.
Of course, by moving off the line, the angle is narrowed, but, hopefully the above is food for thought.