We know the most-likely, but not set-in-stone, starting lineup for Boston will be Al Horford, Jaylen Brown, Kyrie Irving, Jayson Tatum and Gordon Hayward. But as the season wears on, and the playoffs arrive, fatigue and injuries will make the second unit vital for success.
Lineups will definitely change depending on the match-up, but the second unit will most likely be Marcus Smart, Terry Rozier, Daniel Theis, Marcus Morris and Aron Baynes. Theis did not participate in the playoffs last season due to knee surgery, but Smart, T-Ro, Morris and Baynes took on larger roles due to the absence of Gordon Hayward and Kyrie Irving.