It seems so long ago now, but a turning point to this Cavaliers’ season was the growth and development of a viable bench unit. With veterans like Luke Walton, Shaun Livingston and Wayne Ellington guiding the reserves, the Cavs built major equity with that second unit. Now as they prepare to face the Boston Celtics tonight, the Cavs have made plenty of withdrawals from the bench. Injuries to the starting backcourt have wrecked the rotations and any depth the Cavs worked so hard to build. Livingston and Ellington are now starters. Long forgotten guys at the end of the bench like Daniel Gibson and Omri Casspi are starting to play meaningful minutes again and journeyman Chris Quinn, signed just last week, is already one of coach Byron Scott’s top reserves because he simply doesn’t have many other options. “We’re still kind of searching,” Livingston said. With 13 games left in a long, grueling season, this is hardly the time to start shortening the bench and extending guys’ minutes. But Scott is left with few other alternatives. Livingston has averaged 33 minutes since Kyrie Irving was injured. Ellington played 41 minutes in that crushing loss to the Miami Heat and can likely expect to play at least 30 minutes a night between now and the rest of the season — or when Dion Waiters returns, which doesn’t seem likely. The Cavs offered no concrete timeline again Tuesday for either of their promising guards. The initial plan for Waiters was to rest him a week and see if there was improvement in his left knee, which has a loose piece of cartilage affecting his ability to run and move. The Cavs were hopeful a week of rest and treatment would allow the fragment to work itself out, but that obviously hasn’t happened yet. No one is mentioning surgery, but it remains a viable option.