I would say, Giddens, Cassell and Scalabrine begin on the inactive list with Giddens going to the NBDL. Ultimately, I see either Giddens or Scalabrine as a regularly listed inactive player all season. But, Scalabrine and Cassell could play due to injuries.
The minimal twelve active players for Boston will likely be: Pierce, Garnett, (Ray) Allen, Rondo, Perkins, House, (Tony) Allen, Powe, Davis, O'Bryant, Walker and Pruitt.
One player still must be removed from the sixteen players. I remain convinced that Miles could be the subtraction.
In the event that Miles shockingly makes the team, your inactive list could possibly be Miles (ten-game suspension), Giddens (NBDL) and Scalabrine. So, it's imperative for Cassell to be named an assistant coach rather than a player seeing as his contract is guaranteed. But, I think Ainge likes the flexibility he affords Rivers with having an emergency point guard in veteran Cassell behind Pruitt. Makes sense. While retaining Miles doesn't... You've Powe behind Garnett and Walker behind Pierce. Not to mention, Tony could see time at the three in a smaller lineup off the bench with Walker at the four like G. Wallace is at times with the Bobcats.
Understanding how rosters are set under the new CBA
Under the new Collective Bargaining Agreement, each team is required to carry 12 players on its active list and at least one player on its inactive list. Teams may have a maximum of three players on its inactive list, which includes any players sent to the NBA Development League.
http://www.nba.com/news/inactive_rules_0506.htmlEach team is required to carry 12 players on its active list and one player on its inactive list (which will replace the injured list). Teams may have a maximum of three players on their inactive list (subject to hardship rules, which will apply in the event that a team with three injured players on its inactive list has a fourth player that suffers an injury). Players sent to the NBA Development League (see below) will continue to count on a team’s inactive list.
The league has agreed to guarantee that, on a league-wide basis, teams will maintain an average roster size of 14 players over the course of the season.
http://www.nba.com/news/cba_summary_050804.htmlSection 1. Active Roster Size.
Each Team agrees to have twelve (12) players on its Active List and to have a minimum of eight (8) players on the bench for all Regular Season games. Notwithstanding the foregoing, any Team may from time to time as appropriate, but for no more than two (2) consecutive weeks at a time during the Regular Season, have eleven (11) players on its Active List.
Section 2. Inactive Roster Size.
Each Team agrees to have one (1) player on its Inactive List for all Regular Season games. Notwithstanding the foregoing, any Team may from time to time as appropriate, but for no more than two (2) consecutive weeks at any time during the Regular Season, have no players on its Inactive List.
Section 3. Minimum League-Wide Roster.
(a) For each Regular Season covered by this Agreement, NBA Teams shall, in the aggregate, employ an average of no less than fourteen (14) players per Team.
http://www.nbpa.com/cba_articles/article-XXIX.php