I can't honestly say I've paid a lot of attention to the trade deadline during my brief time in the league, so I'm not exactly sure how active/inactive the trade deadline is. I'm not even sure where to look to see where trades are posted or when the trade deadline even is for that matter. 
It does mostly seem that there is a cycle of perennial elite teams and bottom feeders, wherein the lower teams seemingly tank as much as possible to draft as high as they can for a stretch of a few seasons and then essentially wait and see if those picks/players pan out. Those teams aren't in a rush to be making moves at the deadline, while others like San Francisco are so good they don't need to make moves either. 
Does anyone in the mushy middle want to make trades while they're seemingly fighting an uphill battle or simply be patient while they build their core and chemistry?

In short, I have no idea.