How does Zen Ball work?

I've been playing Peggle for a very long time, but I still don't know everything there is to know about Zen ball (master hu).

Here's what I know (or at least think I know). Feel free to correct any of my assumptions or offer any other interesting facts. I'll give the answer to whoever provides the most useful or interesting insight into the algorithms behind Zen ball.

• Zen ball will simulate a few (maybe all?) possible shots within a certain arc of your beginning shot and improve the shot based on the ending score of the shot.
• After calculating, a percentage will usually appear (i.e. "240% more zen achieved") - This is the amount the score improved with the shot that Zen ball has given you.
• The calculation factors in style points when choosing which shot to choose.

Some things I would like to know:

• Sometimes it won't list the percentage increase in zen, but simply "Zen Achieved" or "Maximum Zen Achieved." What do these mean and what's the difference?
• Based on my own experience, I feel like Zen Ball may have gotten a nerf between Peggle and Peggle Nights. Is there any truth to this, or am I imagining things?

Firstly, Peggle is awesome and addictive.

Next, to answer your questions, this is what the Zen Ball does, courtesy of the Peggle Strategy Guide:

When the Zen Ball is activated, the wise old owl considers a range of possible paths for the ball based on where you aim your shot. He nudges your aim toward the highest-scoring path, with additional weight on dropping the ball in the Free Ball Bucket and lighting up orange pegs.

After you take the shot, Zen Ball will tell you how much it has improved your shot. "No improvement" means Zen Ball has not improved your shot. "Zen achieved" means your shot has been improved (by dropping the ball in the Free Ball Bucket, for instance) but not for additional points. "(Some Percentage) More Zen" means that your shot has been improved by the given percentage. "Maximum Zen" means your shot has been improved by more than 500% over the original shot.

I can find no evidence that support that style points are also calculated. However, speaking from my own experience, when Zen Ball achieves its max potential, that usually gets you some.

Also from my own experience, I do suspect that the Zen Ball is less effective in Peggle Nights. However, I cannot confirm this.

Some additional tips to consider when using the Zen Ball:

• The Zen Ball works best when there are lots of angles to consider. Aiming directly at a peg or the corner of a brick offers more possible angles and brings maximum Zen magic.
• Shoot the Zen Ball at pegs high up on the screen to get as many other pegs on the way down as possible.

Most Effective: Zen Ball is useful on just about any board, but it's best to use it early on. The more orange pegs on the board, the more options it has.