Look at this from the eyes of a business owner.
Bringing in Sam last year showed management and the coaching staff that Sam's days as a player are probably all but done but if in an emergency he is needed, he could probably add something to a team this year. Also, Sam showed an amazing ability to communicate with the younger players in a teaching role and management found out he would probably be a great coach someday that they could use.
So, knowing that and the fact that the Celtics were committed to 14 roster spots this year, what would be the best way to keep Sam as part of the fold while keeping all options open and spending the least amount of money.
Simple, sign Sam to a veteran's minimum contract that the league subsidizes. Sam will be the 15th player on the team, inactive most nights in a suit, coaching up the young guards. So if Sam is needed in case of an emergency, he's readily available. He's still coaching, just not being called a coach. And the NBA is picking up nearly half his salary.
Now if Sam was just a coach he'd be making coaches pay and we would most likely have another vet min guy on the bench. We'd be paying our portion of the vet min, same as if Sam is the 15th guy, but we'd also be having to pay Sam a coach's salary. And on top of that if House goes down, we'd have to cut the veteran eating that contract, end Sam's coaching contract by firing him, probably eating that contract and then have to sign Sam to the vet min contract anyway. The Celtics might end up throwing away about $1.5 million that way when the current way is just so convenient and inexpensive.
