Perhaps it could be put this way.
Is Cap space an asset to a GM?
Yes, "some" space is needed to allow for deals coming in and going out but, is cap space an asset?
If a GM is under the cap, they can use the space to help with deals, but, is cap space an asset?
No, it really isn't an asset, it is a function of managing other assets within league guidelines.
The current Boston Celtics roster is quite well structured with contracts expiring of varying size and dates.
Contracts are what could be viewed as "assets." They allow for correct "packaging" of deals to acquire players that you want.
If Ainge wants Lebron James he must create the necessary $20M+ space, but, why the he*& would he do it far in advance?
Humphries contract is an asset in a deal, the space it creates when it expires is a "moment in time" before it is filled with other contracts.
This deep semantics stuff is killing me..."a moment in time" a "function of managing assets..." I think I just passed out and woke up at M.I.T...uh oh....security just got here