#2 Daniel Theis
Daniel Theis went undrafted during the 2013 NBA draft, although the German eventually made it to the NBA after starring for the Brose Bamberg in the German league. Thies' performances led to the Celtics signing him back in July of 2017, and the 26-year-old went on to play 63 games in his rookie season, averaging 5.3 points, 4.3 rebounds in 14.9 minutes per game.
Theis has continued to play a similar number of minutes during the 18/19 season, although the Celtics are currently stacked at the center position, and the German's minutes are likely to be reduced considerably during the playoffs. Theis is also set to become a free agent during the summer, and the Celtics will consider trading the center away as the entire Boston roster is currently fit and healthy. The German could attract interest from teams such as the Rockets, so a trade looks likely.