It’s the right time. DL has done a great job and deserves credit. There are some teams that have done better in the last 9 years, but not many that are in similar market sizes and started with the same lack of assets.
With exceptions in Miami and San Antonio, it is a bit of a new normal for one GM to build a foundation and then another GM to come in and take the team to the next level. Meyers in GS, Ujiri in Toronto, Pelinka in LA. If Phoenix ends up winning a championship you can add Jones to that list as well. None of those GMs started the championship build, but each made key moves/roster changes that elevated the team to championship level.
At a certain point you just become too attached to your own players (eg, Exum, Favors, Ingles contracts/extensions) and it impacts your judgment. A fresh set of eyes can work wonders.