If I'm picturing this correctly, you come into your slip bow first and the forestay hits the two lines in the center of the X so that those lines kind of hold the boat still long enough to get your dock lines on?
Not exactly... the lines are only dock height except for the one coming off the pylon. At the bow it's probably 2 feet off the water. As the line goes down the starboard side of the boat the height of the line increases as it gets closer to the pylon. This added height helps keep me from getting close to my neighbor if the wind is blowing on my port beam. If its blowing across my starboard beam it'll just push me towards my finger pier. The "X" keeps me away from the dock and my dock box. It actually holds the stern just out of the slip. This will only allow the stern to move between the pylon and the finger pier. It's worked great so far.
s/v Puggin Along
1988 Catalina 30