16. Al Horford, Boston Celtics
At 38 years old, it may be surprising to see Al Horford on this list. In fairness, the biggest reason why he's on this list is because he'll be filling in for Kristaps Porzingis in the Boston Celtics starting lineup to open the season. But even if he were the full-time starter for the Celtics, there's reason to believe that he'd be considered a league-average starter. Horford started 33 games last season for the Celtics and still managed to average nine points, six rebounds, and three assists on 51 percent shooting from the field and 42 percent shooting from 3-point range.
Horford may no longer be the elite defender he once was during his prime but he still manages to be in the right place at the right time defensively and has developed into a lethal 3-point shooter. Horford may be a league-average starting center but he's arguably the best backup center in the league.
Part of the reason why the Celtics are so dominant is the fact that they can slide Horford as a starter in the absence of KP and not miss all that much overall.