Let's assume for a moment that the rumors are true that Boston can't trade #3 for any of their ideal targets (Middleton, Parker, Cousins, Hayward, Butler).
Let's also just assume for a moment that Kris Dunn is the pick at #3, because even if we don't get a deal done pre-draft, we can entice Philly into a trade using Dunn.
Who has less Leverage?
Philly: Thanks to Simmons, Philly has no major pressure to win immediately. It's widely known they need a guard at some point.
- They claim they will play Simmons as an unconventional PG.
- As many still point out, there's a chance Saric stays overseas, but might actually be a SF anyways.
- They have two starting bigs in Okafor/Embiid with Noel off the bench.
Celts: There's immediate pressure to improve. They are lacking in size.
- They have two starting guards in Thomas and Bradley with Smart off the bench.
- They have three more 1st round guards they didn't have minutes for: Rozier, Hunter, Young
- If they draft Dunn, that's a 7th guard they likely don't have minutes for unless Smart loses a lot of minutes.
- They have 7 additional draft picks that they probably don't even have roster spots for.
Both teams are dealing with log jams in that scenario. Philly and their 3-5 bigs. Boston and their 7-14 guards.
It's already been reported that Celtics have the upper hand in this scenario, because 76ers desperately want Dunn. I would agree with that.
Boston actually has very little pressure - they would like to make a trade that improves the team now, but if they can't do it then they have 8 draft picks that they can use to try to fill needs, and they have about $50M in cap space to work with once the FA market opens...and they have other potential lottery picks in 2017 and 2018.
If the reports are true then Philly is desperately trying to ditch Okafor to Boston, but Boston prefers Noel and isn't incredibly interested in either...
Reports were that Boston really liked Brown, while Dunn and Bender could have significant trade value if Boston drafts them and they impress early on. There's still the option of Hield as well, as he can likely fill a need right now (shooting / scoring) in the event Boston can't pull a Middleton / Hayward in.
I think Boston is under less pressure then almost any team right now, simply because they have so many options available and there really isn't any "bad result" here. Worst case is that no deal happens and they draft for potential (Bender/Dunn/Brown) or need (Hield). Three of those four guys (Dunn, Brown, Hield) could likely contribute from day one, so it's no big deal at all if that ends up the case.
Sixers on the other hand REALLY need a point guard desperately - Simmons at PG might be their solution worse case, but it's hardly optimal to depend on a 19 year old 6'10" rookie to be your starting PG.