I'm wondering if Philip might have been right, though, that it might be better to create three groups instead of two: (1) out events, (2) reaching base events, and (3) balls/strikes.

The ball/strike events are less important than the out/reach base events, so maybe somehow they should not be given equal graphical weight. To me, the interesting thing is the length of the at-bat, not whether any particular pitch was a ball or a strike. So maybe the ball/strikes just get a little dot instead of a little line, so the data is still there, but it's more easy to ignore.

This is hard to explain without drawing it myself, but perhaps there's a way to put a box around each AB so you can tell at a glance the outcome of the PA. So the box would always contain the ball/strike sequence, plus would either extend up to contain the out, if it results in an out, or extend down to contain the hit/walk/error if the runner gets on base. (Let me know if that makes sense, otherwise, I can try to email you a drawing of what I mean.)

You mean like PECOTA?

"Pitcher's Enhanced Chart of Total Accountability"

(or not ...)

Also known as ARMAS.

Looks like something that Ed Tufte might put together.

I also recall there being something similar (zip chart or something?) that I think I saw on Baseball Musing website, but much more simpler than your concept. But if you can find the programmer, he might be able to modify his prior work to fit your format.