I think the following is much clearer.
in reply to Re: I wrote some clever code - can the comment "defuse" it? (stab at restructuring)
in thread I wrote some clever code - can the comment "defuse" it?
Saving the run lengths in a temporary does help readability. The only nit I have with the otherwise good updated version is that it destroys @letter from within an expression. In this case, it's what you want, but it risks a "Hey, what happened to my letters?!?" if someone else tries to reuse the snippet later.