Relief pitcher Matt Bush has a torn UCL and will undergo Tommy John surgery, per the beat guys on Twitter. This will result in him missing the rest of the 2019 and almost certainly all of the 2020 season.
Bush had surgery in September of last year to repair a partial tear of his UCL. He had returned to action this summer after missing the first part of the year as he rehabbed, and had been outstanding for AA Frisco, leading to speculation he would be called up to the majors before this latest setback.
Bush is a former position player that converted to pitching, and I have a theory (which is based on nothing more than my gut feeling based on what I’ve seen) that converted position players are more prone to UCL tears than players who have always been pitchers. He will be 35 at the start of the 2021 season.