Adrian Wojnarowski noted in the proposed Kyrie Irving swap that "Cleveland had significantly valued the 2018 Nets pick in the trade..." That statement implies the Cavaliers don't have much faith in their current roster remaining at a championship level without help from a lottery pick.
By the same token, with their numerous draft picks the Celtics trust in their current players winning the NBA Finals seems shaky at best. The uncertain situation about the futures at both franchises make the stable situation in Miami seem appealing in the stormy seas of the NBA.
This season the Cavaliers and Celtics are clear favorites for the Eastern Conference title. Beyond that point though, their status could deteriorate more rapidly than generally assumed. Meanwhile the Miami Heat have a clearly defined plan for their future success that focuses on grooming the talent they already have to elite status.
Frankly many of the players on the Heat have a long way to go before reaching the top-15 talent level, if that’s even possible for most of them. That sounds harsh, but it seems the Cleveland and Boston managements don't believe their players will become any better than they are now. On the other hand, Miami staff and coaches feel they can replicate the success they had in bringing players such as Hassan Whiteside, James Johnson, Dion Waiters to another level.
This season Kelly Olynyk needs to elevate his game much further then ever before, while at 20 years old Bam Adebayo is just starting to learn the NBA ropes and needs time to make an impact. Rodney McGruder and Okaro White were rookies last season, so whatever upside they has yet to be determined. Justise Winslow and Josh Richardson now realize success in the NBA is more difficult then they ever imagined, and along with Tyler Johnson, will have to work harder than ever if they want to achieve that elusive All-Star status.
This was a long-winded way of saying the stability of Heat Culture makes players believe they can develop into something special, if and only if they develop the necessary skills to reach that level. By design Heat management has given players a security, which is theirs alone to lose by not meeting expectations of a championship.
The eagerness of the Celtics and Cavaliers to go after draft picks implies a vote of no confidence in their present roster staying together. While this season for the Heat doesn't seem destined to bring the ultimate trophy, the turmoil elsewhere suggests it will come back to American Airlines Arena sooner than expected.