4. Mason Plumlee
Mason Plumlee has had an underappreciated career. At 34, he's still a serviceable role player. Last season with the Los Angeles Clippers, Plumlee averaged 5.3 points, 5.1 rebounds, and 1.2 assists per game. As mentioned with Watford, the Blazers need more versatility on their roster, and Plumlee would help in that department. For Watford, it was shooting, but Plumlee's standout trait for a center is his playmaking.
Plumlee has a high basketball IQ and consistently makes the right reads. Having more big men depth can't hurt, especially if they are versatile enough to give teams different looks. The main question is whether Plumee would even be interested in a reunion with Portland. At this stage in his career, Plumlee likely wants to be on a contending team. If he did go to a lottery team, it would only make sense if it was for an increased role or salary, neither of which the Blazers can offer.
But, two of Plumlee's best seasons in his career were with the Blazers. In the 2016-17 season, Plumlee averaged a well-rounded 11.1 points, eight rebounds, four assists, and 1.2 blocks a game. Perhaps he wants to relive his glory days.