She worked so hard over the summer, so it must have been demoralizing to have to go through injuries again. Just the thought of going through all that rehab and practice again probably made her sick. Maybe she might get the fires burning again, but her injury is chronic so I doubt it. Same thing happened to Christina Wheeler after she won the WC play off a few years ago. Worked so hard to get back up there, but quit with a back injury not long after.
I remember standing outside Margaret Court Arena at the Aussie Open this year. The arena was absolutely packed and impossible to get in without a massive wait in line. I was watching the live scores on my phone and the internet connection kept dropping out. Boj was up 5/4 and serving for the set against 4th seed Radwanska, and the crowd was going nuts. Unfortunately she did not win another game and after a steep downward fall due to injury now retires. This is heart breaking.
Pity, nice girl, easy to talk to, and looked like could go somewhere, especially last year. Solid game for most part. At least has a college education so has options to do something else in the Corporate world beyond tennis. Good luck Boj.