I don't think the Celtics have a good number 1 at the moment. Rondo can be the best player in a series. But he doesn't have the scoring ability to take you all the way to the top of the mountain like an Isaiah Thomas.
1. ?
2. Rondo
3. ?
4. Green
5. Sullinger could evolve into this within a year
6. Bradley shows potential to become a 6th best guy on a contender
7. Bass
8. Wallace
8. Crawford, Olynyk, Faverani show potential to be 7th or 8th men in a couple years.
9. Lee, Humphries
But I do think Rondo is a quality second best player on a finals contender. (Other number 2's have included: Wade, Parker, Westbrook, Chandler, Pau Gasol, Pierce, Billups, a young Kobe)
Then Green is at least a quality 4th best player on a finals contender (along the lines of a 37 year old Ray Allen, Battier, a young Ibaka, a young Andrew Bynum, a young Rondo, a 34 year old Mike Finley, Antoine Walker on the Heat, etc.)
Sullinger could become a solid 5th best player along the likes of Perkins in '08, Artest, Chalmers, Terry, Bruce Bowen, Horry, Haslem in '06, etc.
Here are some 6th -8th men from past Finals teams:
6th: Mike Miller, Splitter, Haslem, JJ Barea, Fisher, Posey, Corlis Williamson, Malik Rose
7th: Battier at age 34, Diaw, Deshawn Stevenson, Farmar, PJ Brown in '08, old Gary Payton, old Brent Barry, Okur.
8th: birdman, Neal, Brian Cardinal, Vujacic, Tony Allen, young Gortat, old Mourning, old Linsey Hunter.
Let those 6th-8th names sink in. The Celtics are full of guys that could swap into those roles. True contenders tend to have pretty wacky rosters outside of their top 5 or 6.