The Cowboys lost DeMarcus Ware, Anthony Spencer, Jason Hatcher and Jeremiah Ratliff during free agency, and Jones has admitted that he was frustrated by the amount of injuries his side suffered to those key players in 2013.
Jones told reporters: "When we were sitting here last year we thought we were better because we thought Ware was going to be Ware and Hatch was going to be Hatch and Spence was going to be Spence and Rat was going to be Rat.
"And those were pretty damn good football players before the injuries hit. This time last year, we loved our front because I thought everyone was going to be healthy and back and they didn't.
"If we play better on defense, then we should be a better team. Maybe [Jeremy] Mincey and [Henry] Melton and [Terrell] McClain and whoever we draft end up being healthier than those guys, so we end up being better."
The Cowboys missed the playoffs for the fourth season in a row in their 2013 campaign.