I don't know much about him, but it seems like a great arm to gamble on. I wouldn't count on him in 2019, as his second surgery was the end of March 2018, and the second TJS usually requires around a year and a half of rehab.
The good news is it looks like the White Sox have 4 years of control.
https://www.ajc.com/sports/baseball/strikeout-factory-lindgren-has-second-tommy-john-surgery/YTpJQgpEa7AhDZ5XOsP8vI/