The sophomore from Pennsylvania received plenty of buzz when he came to campus in 2012 as a player that could make an impact on the field early.
It didn't happen as his first opportunity came after a redshirt year, which he admitted came with some frustration.
"It's always frustrating," he said. "I was frustrated my freshman year, but you kind of just have to accept that you've gotta keep progressing and keep getting better and wait for your time."
Last year, he had six tackles, playing all 14 games. Most came on special teams, but when he got in on defense, Cox said there was a greater knowledge – one gained by redshirting as he found it helpful.
"Right now, I pretty much know all the defense," he said. "Redshirting my freshman year and then last year, I tried to contribute as much as I could.
"Now, this year I think it's a time I can make some plays."
Both Cox and Williamson said competition is a constant at Michigan State and something welcomed, as is the mentality of the "next man up."
"It's good competition," Williamson said. "That's every year and that's everywhere in spring ball. I'm sure even after the spring is over, during the camp, it will be a competition between me and him and the future guys coming in. …
"We are taking one day at a time and we are each getting better and I look forward to it each and everyday."
Cox said it has been that way since he came to campus. He also pointed to the culture of competition that has been created in the secondary for the reason coach Harlon Barnett gets the best out of his players.
"It definitely makes you better and that's exactly why Coach Barnett brings out the best in guys because we compete every day," he said.
Now, as he works to get on the field more as a sophomore, there are a few attributes he feels he can bring to the field.
"I definitely believe that I can make a lot of plays, I add depth and can fly around and bring some enthusiasm and life to the defense," he said.
But when he does get on the field, he can point back to the redshirt year and the frustration as having helped get him there.
"Everything happens for a reason," Cox said. "I remember in the spring last year I pulled my hamstring and it kind of let me step back and learn the defense and see everything from a different perspective. I feel like everything happens for a reason. I can make more plays now that I know what I'm doing."