I don't know if you are being intentionally naive or if you really don't understand the history of issues surrounding Dez and how people like David Wells helped him stay out of trouble.
People around the Cowboys refer to David Wells as The Wolf, which is a reference to Harvey Keitel's character in Pulp Ficton.
Others just refer to him as The Cleaner:
http://en.wikipedia.org/wiki/Cleaner_(crime)
Dez has done a ton of stupid things, but only a fraction has leaked to the media. The Cowboys had to advance him money at one point to keep him out of trouble for not paying for 600K of Jewelry that he bought and didn't have the money to pay for. The number of times the police were called to his residence in a 2 year period of time was way more than a normal person would experience in a lifetime. It is a big list of problems.
Maybe he has grown past those issues, but it's like an alcoholic losing his sponsor. It increases the risk of repeating past mistakes.
I sort of get this take... but tell me the last time and by that I mean date and name of his last major incident?
The Jewelry incident was his rookie or 2nd season.
The police going to his house thing was proven to be pretty goofy and is rather weak to bring up now.
Those incidents were NEVER proven to involve Dez and there wasn't a single significant one on the entire list.
In fact a couple of them occurred with Dallas playing on the road once the dates were cross-checked and could not have been Dez at all since he wasn't in the city.
The worst thing Dez has been truly connected to is hitting his mom(that he was fully financially supporting and probably still is) with his cap.
That police check stuff was leak crap coming likely from a ticked off Wells.
Wells is not some squeaky clean guy and having a fixer is not a good idea.
Growing up and not needing one is.
The fact all this ancient history stuff has leaked as they part ways tells you all you need to know about Wells and why Dez needs to be rid of him in every way.
Anyone whose watched Dez realizes he is a hothead and prone to get into trouble by acting before he thinks.
But the trouble has never been serious and his work on the field and his actions off have at least seemingly gotten better and better.
He isn't going to pay someone like Wells to babysit in this next contract.
That's what attorneys are for.
Wells didn't come into Dez's life as a fixer. He came in a really rich dude willing to give Dez room and board as he was a year away from the draft.
Perhaps he did all that for no reward but we are taking about a guy who once was an FBI informant in a murder for hire case and who was convicted of tax evasion.
Has he helped folks? Yes. Is he squeaky clean and ignoring his bottom line? Heck no.