"The Chicken or the Egg" - Pass Rush vs Good coverage?

Both of them are needed. But what is the most cost effective way to go? Undoubtedly getting a stud pass rusher. The saying is....in front of every ProBowl caliber CB, there is a ProBowl caliber pass rusher. There is a lot of truth to that. But the opposite is also true....If we go back and look W Smith's production, it certainly gives a valid argument why PRob is so disappointing