Injuries to Collingwood's seasoned small defenders Ben Johnson and Alan Toovey left a void, and Williams has taken his chance.
"I thought I started a little bit slow this year, but since then I've been pretty consistent and been playing my role pretty well, so it's been good," Williams told AFL.com.au.
"I've tried to take over the roles of Ben Johnson and Alan Toovey and shut down those small forwards, that's been my main focus.
"The coaches want us half-backs to tuck the ball under our arms, run and then use the ball well, so that's what I've tried to do."
So impressive has the 20-year-old been in curtailing some of the league's most dangerous goal sneaks, he is the round 18 NAB AFL Rising Star nominee.
Williams is averaging 15 disposals and three tackles from his 10 games this season after playing six matches in his debut year of 2012.
"I wasn't really thinking about it, but I'm stoked to get a Rising Star nomination, it’s a big step forward for me," he said.
One of the driving forces behind his stellar form is the recently retired Johnson, and Williams can't praise his mentor highly enough.
"The injuries opened up a massive opportunity but Ben is doing a lot of work with me on how to play as a small defender," Williams said.
"He's taken me under his wing by teaching me how to cope with their speed, (to) concentrate and put heaps of body contact on them so you can put them off their game."
Williams' form not been lost on his coach Nathan Buckley, who is an unabashed fan of the West Australian's performances since his return to the senior side in round eight.
"Marley’s application to his craft over the last two to three months in particular has been excellent," Buckley said.
"The work that he is done with the development coaches and with Ben Hart has set him up to succeed and we have seen the fruition of that on the field.”
While he is happy playing his role across half-back for the moment, Williams is eyeing a spot in the Magpies' potent midfield along side Dane Swan, Scott Pendlebury and company.
But to achieve that he knows he must work on deficiencies.
"My kicking is something I've definitely been working on and it is certainly improving," he said.
"Hopefully soon enough I'll be able to push into the midfield, that's what I'm definitely striving to do.
"My biggest goal now is hold my spot, keep playing my role and hopefully play some finals."
