In my Amish days, I tried to follow DL's book to the letter.
In my non-Amish days of recent, I have tried to follow more modern programs, (which do not specifically call for walking baseball as part of the curriculum) to the letter.
I am still doing variations of walking baseball.
To me, the purpose is to help the dog transfer the casting mechanics learned in three-handed casting, double T drills and swim-by over to "the field". The drill helps the dog connect the casts as being much more directly related to going in a direction, with respect to his position relative to his handler, as opposed to going to a known location through repetition.
The drill allows the handler to incorporate any host of factors or "diversions" such as: Cover, sidehills, water entries, water exits, cover changes, etc. etc.
I do not think that DL ever intended his drill to be followed step by step in all fields. I think DL intended to show a trainer a way to start the drill in a flat, featureless field. Then he left it to the trainer to add this to his bag of tricks for use later in other locations.
Who knows....maybe my interpretation of "walking baseball" is very different from what DL intended! Maybe my interpretation will be different from the product that it appears Evan will be introducing.
To first learn Walking Baseball, I suggest that one fold an 8 1/2 x 11 sheet of paper in half widthwise then lengthwise, and break the field down into quarters to diagram your drill....start in the one quadrant, work that piece, gradually backing your way out, over and across. After you diagram it once, you should put the paper away and go do it in the field. It is a lot like hanging wallpaper or painting. After you do it a few times, you learn how to plan your steps to keep from getting painted into a corner, or winding up needing a crazy piece of wallpaper to cover a small piece of wall.
Dog training is more art than science. I think that Walking Baseball is a perfect example of where the artist puts together something unique. Each time you build the piece, it will look a little different than the last and you adjust as-needed.
Chris