Any chance Dez had of being on this team ended when we drafted Lamb. They gave Lamb Dez's old number.
While it would be nice to relive the glory days of Dez, there are a number of reasons why Dez is not a good idea.
1. He would be a massive distraction, even if he didn't want to be. Dez in TC would lead to constant questions of both him and the Cowboys about his role. If Dez was silent, that would twisted into meaning he's disgruntled. If Dez talks, then he risks being a distraction. That alone cancels out any risk in having him.
2. Dez's skills were already declining in his last season here. Since then, two years have passed and he has suffered an injury that can often be a career altering injury. Dez likely doesn't have the physical attributes to do the things that made him a game changer.
3. Route running and precision were never one of Dez's strong suits. WR who last when their skill sets decline often do so by being very good students of the game. I do not have faith Dez has this.
4. While there's a chance that Dez has learned and will come in and be a model student, there is a strong chance that Dez would be a bad influence on the WR group as a whole. While I am less worried about Amari, it is quite possible that if Dez's lack of attention in meetings, lack of being a student of the game, and propensity to be late to meetings would rub off on Gallup and Lamb as well as the other young players.
All that equals to Dez not being worth the risk. Surely, if he could come back, work hard, be a great example to the young guys, quietly accept a complimentary role, and not be a distraction, it would be an awesome feel-good story for the Cowboys. It's just the chance that one of those things derails the whole ship is greater than those things working out.