https://www.dallascowboys.com/news/mailbag-should-draft-be-before-free-agency
One of the answers, hit the Jones' theory on the head. Though many fans want to hit them on the head regardless.
Anyway, they sign the bargain basement types, then hit on a player in the draft. If not to replace them right away, but for the next season. Such as the Fehoko types.
Of course they want to get solid players all the way around, FA and the draft. You need to get at least a starter with the 1st pick, 2nd or a lot of playing time, especially with the 3rd round. After that, some contributions for the 1st year from a few others.