The 24-year-old made 17 appearances in the PRO12 last campaign but his form suffered and the scrum-half slipped out of the international reckoning with Wales.
Williams, who has 18 caps in total, hasn't featured on the Test scene since facing Tonga in Cardiff almost a year ago.
Much of that owes to a knee ligament injury but Williams says he wants to get back to full fitness and form with the Blues in the GUINNESS PRO12.
"Last year was disappointing for me, the season sort of slipped away from me towards the end," Williams told Wales Online.
"I wasn't getting much game-time, then I got injured and lost a bit of fitness and struggled to get it back.
"I think maybe I came back a bit early after I was injured and didn't do myself any favours.
"It was my mistake, I learned from it and won't be doing it again.
"Also, things weren't going well for the team and that does make a big difference.
"If you are in a team that is doing well, you will do well.
"It happens, but I've put it behind me and worked hard in the last few weeks."
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