NBA coaches prefer to have their systems in place and lineups set early in the season. However, several contenders need to make crucial rotation adjustments in preparation for the playoffs.
There are many reasons why a team's chemistry may change and a coach's plan must be altered. Injuries play a major role in the development of a team. A coach must compensate for the loss of a player and adjust his rotation once that guy returns.
Changes in expectations or a player's performance may cause a coach to revise his substitution patterns. One individual may fade after a hot start, while another improves as the season progresses. Young players may not develop as fast as expected.
It may take several months for a coach to determine which two, three or five-man units play well together. That process is complicated by injuries and midseason trades or free-agent signings.
Ultimately, a coach is limited by his personnel. Deeper teams possess the flexibility to utilize different lineups, whereas other squads are confined to a specific style of play.