best possible back up PG's in my opinion...
1. Carlos Arroyo
2. Flip Murray
3. Bobby Jackson
4. Brevin Knight
5. Jacque Vaughn
6. Tyronn Lue
wouldn't mind anyone in the 1-4 range
I don't like Murray. We already have an undersized 2 in a 1's body in House. We don't need two. Though I think Eddie ultimately beats most of those guys out--somewhat negating their value--I think a purer PG like Arroyo, Jackson, Knight, or Vaughn would be nice to have in case Rondo goes down for a few weeks.
However, I wouldn't stress too much about it. If Rondo goes down for the season, none of those guys will make up for it enough to still win #18. Furthermore, if he only goes down for a few weeks, any of those guys will be good enough for the C's to win most regular season games.