Honestly, anyone that parrots that "Dez runs sloppy routes" stuff is just repeating garbage they've heard from other clueless people who similarly haven't bothered to do any research.
There's a reason Dez always tells people to watch the tape when this comes up.
Dez's problem, and the problem with all the receivers, has been identified by players, opposing players, opposing coaches, etc.
The team identifies what they think you're good at and that's all they let you do. Every receiver we have runs two routes 98% of the time. No amount of "route running prowess" is going to get you separation when defenders can flip a coin on every passing down on exactly what you're going to do.
If the organization goofed by giving him too much money, or they think he's T.O. and destroying the team from the inside, then get rid of him. If his cap his was 10m this year, there wouldn't be so many people talking crap.
But let's not pretend there aren't obvious problems with the passing scheme.