Designated rookie extensions prevent Boston from getting involved until July. Kyrie does not become a free agent until July 1. That doesn't mean they can't work out in agreement before July 1, but nothing can happen officially with Boston until July 1.BTW., AD and Kyrie are friends and have a strong relationship, and trading from the multiple players Boston will have available to have AD joining Kyrie is much more preferable and would keep Kyrie in Boston.
Here's a summary on Boston from espn.com -- this article also summarizes what the other teams can do (http://www.espn.com/nba/insider/story/_/id/25873573/what-top-anthony-davis-trade-contenders-actually-offer)
Celtics on the clock but not until July 1
A quirk in the collective bargaining agreement has the Celtics in a holding pattern until July 1. However, despite Boston not being eligible to acquire Davis at the trade deadline while Irving remains on the roster under his current contract, both sides can begin to negotiate the framework on a potential Davis deal now.
Starting the process and not waiting until the offseason gives New Orleans a baseline when comparing trade offers from other teams leading up the deadline. If New Orleans knows that an appealing trade package from Boston is within reach five months from now, then New Orleans should wait this out.
Off the table: Kyrie Irving (free agent), Marcus Morris (free agent), Terry Rozier (restricted free agent), Daniel Theis (restricted free agent), Brad Wanamaker (restricted free agent), Jabari Bird (personal reasons)
Draft assets
Own all future first-round picks (2019-2025).
Own Sacramento's 2019 first (Nos. 2-30)
Own Memphis' 2019 first (top-eight protected). Will roll over to 2020 (top-six protected) and 2021 (unprotected). This is the crown jewel of the Celtics' draft assets based on the certain futures of Mike Conley and Marc Gasol.
Own the Clippers' 2019 first (lottery protected). Will roll over to 2020 (lottery protected). If not conveyed, Boston will receive the Clippers' second-round pick in 2022.
Own all future second-round picks except 2019, which will convey to Memphis if it falls Nos. 56-60.
Cash to be sent out and received: $5.6 million
Tradable contracts (2019-20 season)
1. Gordon Hayward: $32.7 million; under contract through 2020-21
15 percent trade bonus: valued at $4.9 million in July
2. *Al Horford: $30.1 million; under contract through 2019-20
15 percent trade bonus: valued at $4.5 million in July
3. Marcus Smart: $12.5 million; under contract through 2021-22
4. Jayson Tatum: $7.8 million; restricted free agent in 2021
5. Jaylen Brown: $6.5 million; restricted free agent in 2020. Brown is extension eligible starting in July.
6. *Aron Baynes: $5.4 million; under contract through 2019-20
7. Guerschon Yabusele: $3.1 million; restricted free agent in 2021
8. Robert Williams: $1.9 million: restricted free agent in 2022
9. Semi Ojeleye: $1.6 million: restricted free agent in 2021
Contract becomes guaranteed if not waived by July 1
*Horford and Baynes have player options and cannot be traded until they opt-into their contract for 2019-20.
Complicating factors
Making the money work with Rozier and Morris (free agents), and/or if Horford and Baynes opt out of their contracts. The Celtics would have only seven players to trade, including the $32.7 million contract of Gordon Hayward.