There are some difficult judgement calls that must be made in order to build an NBA team. 

The longer you keep a team together, the more chemistry they will be able to develop as they work together. There is no doubt that some teams are very apprehensive about making big moves because of this fact. 

In contrast, if your team fails to make it to the postseason enough times, you may want to think about making that major move if you have been struggling. Is there any sense in keeping your team together if they are not able to accomplish their goals? 

Take a look at the Denver Nuggets as an example. It would be necessary for this team, at a minimum, to make a competitive stand in the Western Conference Finals as a minimum requirement to meet their own standard.

NBA NEWS & TRADE RUMORS: Damian Lillard, Portland Trail Blazers & Denver Nuggets Updates

In the event that they are not able to do that, they could make a blockbuster deal at the trade deadline. 

As an example of this, they landed Damian Lillard of the Portland Trail Blazers in this deal, for example.