The Boston Celtics have extended a qualifying offer to big man Daniel Theis, according to Adrian Wojnarowski of ESPN. This makes Theis a restricted free agent and gives the Celtics the ability to match any offer he receives.

Given the fact that Boston traded Aron Baynes and is also likely to lose Al Horford in free agency this summer, the Celtics may actually end up retaining Theis, as they have a very thin and inexperienced frontcourt at the moment.

Theis is coming off of a 2018-19 campaign in which he played 66 games and averaged 5.7 points and 3.4 rebounds over 13.8 minutes per game while shooting 54.9 percent from the floor, 38.8 percent from three-point range and 73.7 percent from the free-throw line.

The 27-year-old, who came over to the NBA from Germany, signed with the Celtics during the summer of 2017. He then went on to have a pretty impressive rookie season, registering 5.3 points and 4.3 boards across 14.9 minutes a night while making 54.1 percent of his field-goal attempts, 31 percent of his long-distance tries and 75.3 percent of his foul shots. However, Theis ended up tearing his meniscus and was knocked out for the season after 63 games as a result.

Boston was the league's most disappointing team this season, winning just 49 games and finishing in fourth place in the Eastern Conference standings in spite of the vast majority expecting the C's to win around 60 games and finish atop the East.

The Celtics were then eliminated from the second round of the playoffs, marking the first time they did not make the conference finals since 2016.