It's common for a team to exercise the fourth-year option for a former lottery pick. For instance, among 2016 lottery picks, only Dragan Bender, Marquese Chriss, and Georgios Papagiannis - who was traded from the Sacramento Kings to the Portland Trail Blazers before being waived early in his second season - failed to make it to the end of their rookie-scale deals.
So it's little surprise Boston would hold onto its rising talent. In two seasons since being selected No. 3 overall in the 2017 draft, Tatum's averaged 14.8 points, 5.5 rebounds, 1.9 assists, and 1.1 steals per game with an effective field-goal percentage of 52%.
Tatum will become eligible to sign a rookie-scale extension on July 6, 2020.