Williams initially suggested Shaun Burgoyne was his preferred option, but the likeable Cassisi said the situation had since been clarified.
"Choco did sit me down when I got the job – everyone who knows Choco knows he's an honest bloke – and he told me the reasons why things might have been formed in the media," Cassisi said at Docklands, where the AFL captains gathered on Thursday.
"He basically said that when [former captain] Tredders (Warren Tredrea) got injured last year, he sat down the two vice captains – Chad [Cornes] and Shaun [Burgoyne] – said to them that they had a bit more responsibility, as the next captain will probably come out of one of those two.
"That was probably fair to say – and those two are very influential at our club – but since then the club went through a process, with recommendations from the coaches and most of the playing group and out of that I got named captain of the club.
"That was the process and Choco told me that from the start. I've been at the club for eight or nine years and coming over from [Western Australia] as a 17 or 18 year old, Choco has helped me as a person to grow up and as a player.
"He's been an important part of my life, on and off the field."
Now that he is entrenched in the role, Cassisi is relishing the opportunity.
"It's going really well. [I'm] probably six or seven weeks into it now and we won three of our four games in the NAB Cup/[Challenge] so we've had a good start as a club," Cassisi said.
"As a captain, when you're winning games, it's all going well. It's been enjoyable and overwhelming, the support that I've had from all of the boys and from the coaching staff in particular. It's been exciting."
Cassisi believed his 2008 season, when he ranked among the elite midfielders in the game, was his best season and he is again looking to up the ante in 2009.
"I think it was an improvement on the year before and it was probably my best year I've had. It was a disappointing year for the club, so you don't take too much out of it really," he said.
Overall, Cassisi believes the Power's impressive pre-season form – winning three of four NAB Cup/Challenge matches – was no surprise.
"We've always had a good core group of players over the last few years," he said.
"We let ourselves down a bit last year in some games and we were disappointed with that and there is a steely resolve among the group to improve and that was noticeable from day one of pre-season.
"With the new fitness coach and strength and conditioning coach, they really got the ball rolling and we're confident in our game plan, after the last three or four weeks.
"Little things add up that show me that we're going to be a better team this year and as a group, we're looking forward to having a good season together."
As for speculation surrounding Williams' future as coach and the long-term outlook of the club, Cassisi said there was one remedy for that.
"For outsiders looking in, certain things are thrown around in the media … but obviously if we win a lot of games during the year, it's going to make life easier for the club and certain individuals that are involved in it," he said.
