I have never understood why we have to have a "second unit"! Can't an accomplished, professional level head coach establish a substitution pattern?
By that, I mean, at various moments throughout the game, you bring in 1 or 2 players to give your starters a rest, staggering which starters get rest at various intervals. So, basically, at all times, you have 2-3 starters (minimum) on the floor. And throughout the game, starters are getting rest, other than at the beginning and ending of halves.
Glenn Davis thrived last year as a starter, and if he were paired with Perk, Rondo and Ray (or Paul), I suspect he would be much more effective. Same with Rasheed if he were on the floor with KG, Rondo, Ray (or Paul). Imagine Nate subbing for Rondo with the starters. He would/could not be a ballhog with KG in his face. Or Marquis out there with KG, Ray, Perk and Rondo (or Nate).
Danny has got to lay down the law with Doc and make him substitute players in for the starters at various points throughout the game, without killing the starters' flow of the game. IMHO, only when Doc learns how and when to substitute (and not wholly destroy the flow by removing all or nearly all starters), will this team prevent the monumental collapses they have been suffering through this season.
The starters are getting older (prof. sports wise) and need rest during the game, and should get it. They just don't all need to be sent to the retirement home en banc for a quarter at a time. Their rest should be staggered.
Finally, consider this, imagine KG or Pierce sharing their insight into plays while on the bench with Glen Davis (KG) or Nate (Pierce). They could truly impart gametime mindset and realtime analysis of how to attack the opposing team or defend better.
Just my thoughts on the collosal failure that has been Doc's "second unit" substitution practices.