Layman was the 47th pick in the 2016 NBA Draft, originally by the Orlando Magic before being traded to the Portland Trail Blazers in exchange for cash and a future second-round pick. After playing sparingly in his first two seasons with Portland, Layman emerged as a big piece in season No. 3, averaging 7.6 points and 3.1 rebounds in 18.7 minutes per game. He scored 20 or more points four times during the season. Layman signed with the Timberwolves in the 2019 offseason.
Layman attended Maryland. In four seasons there, he averaged 10.2 points and 4.8 rebounds per game while shooting 36.2 percent from the 3-point line. As a senior, he averaged 11.6 points and 5.3 rebounds per game while shooting a career-best 39.6 percent from the 3-point line. He helped Maryland to the Sweet 16 as a senior, scoring 27 points in the team's second-round game against South Dakota State. Layman was a Third-Team All-Big Ten Media selection in 2015.