Theis, 25, has played five professional seasons in Europe. He spent the last three years with Brose Bamberg of the Basketball Bundesliga (BBL), also known as the German Basketball League.
The 6’9 big man averaged 9.5 points, 5.6 rebounds and 1.2 blocks and 18.9 minutes per game last season, and was named the league’s Defensive Player of the Year. Over his career, he has shot 37.1% on three pointers with 140 total attempts.
Today is the day! I'm so excited to join the @celtics family and to live in this great city! I will work my heart out for #Boston pic.