Question is do you want to exceed the cap for a couple years while the organization is rebuilt, then when you have young talent arriving, you have to stay under the cap b/c penalties accelerate if you go over for too many years.
One step back trades aren't for A ball prospects, but AA/AAA prospects who are no more than a year away, filling the donut in the organization, and providing some young players that allow you to sign a major FA in a year or two b/c you have cheap young talent.
Right now, the Phillies have to exceed the cap to make major signings, because they need so many patches.