The problem with a "top ten" list is that it doesn't account for the differences in talent between players, just how they would rank. It's possible that 1-2 are MVP-caliber players, then 3-6 are the next level, the multiple all-star level. 7-9 are the guys who make the all-star team a couple times in their career but are not regulars. Finally 10-16 are talented guys who have long careers but aren't quite stars. Between each tier there could be huge gaps in ability. The 10th best SF for example might be a closer in talent to the 20th best SF than the 1st.
Looking at the top SFs, the depth is not there so Green is probably in there around 7-10. However, I'm not sure what kind of conclusions you can reach from that because the drop off is so steep.
Top SFs (rough ranking):
1. LeBron James
Kevin Durant
Carmelo Anthony
Kawhi Leonard
Rudy Gay
Nicholas Batum
Gordon Hayward
Chandler Parsons
Jeff Green
Trevor Ariza
Kyle Korver
12. Luol Deng
I would probably put LBJ and Durant in the top tier, obviously. Carmelo is in the 2nd tier by himself, with Kawhi and Gay in the 3rd tier. After that you have about 5 or more guys that are roughly similar in value, though of course that is subjective. The thing about that group of guys is if they are the number 1 or 2 options on their team, the team is probably bad. Of course, some of the players on the list are still quite young.
Ok Power Forwards (again, a rough ranking):
1. Anthony Davis
DeMarcus Cousins
Kevin Love
LaMarcus Aldridge
Tim Duncan
Chris Bosh
Blake Griffin
Dirk Nowitzki
Al Jefferson
Serge Ibaka
Paul Millsap
12. Derrick Favors
Looking at this list, I guess you meant Bradley is a top 10 SG? I don't really see Sullinger as being better than these 12 players, at least not yet.
SG:
1. James Harden
Kobe Bryant
Klay Thompson
Dwayne Wade
Dragic or Bledsoe depending on who you consider SG
DeMar DeRozan
Monta Ellis
Jimmy Butler
Wesley Matthews
Bradley Beal
Danny Green
Lance Stephenson
Victor Oladipo
Joe Johnson
15. Jamal Crawford
I guess if you really tried you could squeeze Bradley somewhere into a top ten with that group of players, if you consider his defense to be the additional skill to push him ahead. Personally I think his defense has dropped off and is now a little overrated.
Anyway I guess I sound a little negative but I don't feel like we have three "top ten" starters, and even if we did it just goes to show that once you get into the teens the talent drop off is significant. Actually I'm not even sure if such a statement necessarily means anything - you could even take it to be negative: "Three of our starters are ONLY in the top ten at their position."
It could all just be a different way of saying "We really, really need two top-5 players at their position to make all these other top-10 guys on our team look better."
EDIT: Sorry, I did read your original post but forgot that you did mean Sullinger and not Bradley.