The problem is this: Ainge & Stevens want to play some of these guys under the false pretense that their value will increase with minutes. Well, when Jeff Green checks out and Bass is confused about his role and Evan Turner is thrown out there to play the point, and your team is losing by 20 to a crappy Charlotte team w/ no Stephenson and no Big Al, it defeats any purpose you had to play those aforementioned veterans.
Teams don't want to pay the price Ainge wants, so instead of taking what they can and moving on, they stubbornly continue to play them and hope for the best. Meanwhile, our young guys and others who might actually have a role on this team in the long term, sit and waste what could be valuable playing time.
What we're left with is a team that's the very definition of mediocrity, while hurting our future, all at the same time...YAY!