This is really cool. I never thought we’d get an answer to this one. My friend Rich Fisher at the Vickers Machine Gun Collection & Research Society posted a video on the old chestnut that “the whole nine yards” refers to the length of machine gun belts. As he shows for the Vickers and I’ve covered in general, it really isn’t. Thanks to his comments section I was referred back to the Wikipedia page on the phrase where, it turns out, someone in the last decade found not only a much earlier cite than the 1907 baseball reference but what is likely to be the true origin of the phrase. It comes from an old joke story about a judge who asks someone to make him three shirts out of nine yards of cloth only to receive a giant shirt made from “the whole nine yards”.
Although we’re lacking a “missing link” between the two, the expression must have gained currency from there, perhaps initially as a way to say someone wasn’t up the task and was trying too hard to compensate. If so, it then morphed slightly into the more positive form from 1907 (and indeed to this day), used any time someone gives maximum effort or gives “110 percent”. Alternatively the phrase simply got remembered and repeated (went “viral”, effectively) while the the long and not exactly hilarious joke itself was forgotten. I wanted to share this with readers even though the answer is now prominently displayed on Wiki for all to see because, like me, you probably don’t check on specific Wiki pages very often.
The BS Historian 
