Cincinnati Bengals fans, get used to this picture.
Williams had become a liability in Dallas after a stellar start to his career in which he went to five Pro Bowls, although he probably deserved only three.
In the last few years he was routinely beaten in coverage, missed numerous tackles going for the big hit instead of wrapping up, and took poor angles on many occasions.
The latter ended up making him infamous. As the result of taking poor angles, he was running ball carriers down, grabbing them around the collar, and jerking them down from behind. The NFL decided to make this a penalty in 2005, calling it a "horse collar" tackle—but it was also widely known as the "Roy Williams rule."
I read an article stating that Williams being reunited with defensive coordinator Mike Zimmer will be good, as Zimmer can "design a defense that emphasizes his strong points."
The only defense that emphasizes Williams' strong points is one in which he is taken out during all passing situations.
When Williams broke his arm midseason in 2008, the Cowboys' passing defense stopped giving up long passing touchdowns. They had already limited his plays during passing situations, but teams always seemed to find him. The injury seemed to eliminate the major secondary issues. Let's call it addition by subtraction.
Zimmer may know Williams well, but the key to Williams' early success was not youthful athleticism or Zimmer's defensive game plan; it was ex-Cowboy safety Darren Woodson.
Woodson was the brains of the Dallas secondary for many years. He told Williams where to line up, what to look for in certain situations, and put him in position to succeed as a young safety.
What Woodson didn't do is explain to Williams why he was telling him these things, which resulted in Williams never learning a thing. Once Woodson retired, Williams' effectiveness went downhill (Woodson said this on ESPN, but I cannot find the quotes anywhere).
As Williams began giving up long touchdowns because of poor coverage, Cowboy fans became very discontent and started calling for his release. At the end of the 2008 season, the Cowboys organization finally realized what the fans had seen for the last few years, and Williams was cut, saving them $2 million against the cap.
Bengals fans are getting a fierce competitor who, when in position and using proper technique, can lay the wood like none other.
It's just that they are going to see a lot more of him chasing people down from behind after getting beat, and in the end, it really isn't worth it.