PREMIERSHIP midfielder Xavier Ellis admits he was "as fat as a house" shortly after leaving Hawthorn, revealing he even split his suit in an embarrassing moment at the races.

Ellis was an injury-riddled free agent who had missed out on Hawthorn's 2013 premiership when newly-appointed Eagles coach Adam Simpson lured him across to Perth.

It was a big punt at the time, but one that has paid off handsomely for West Coast.

Ellis has managed 31 games during his two years in the west, helping the side reach Saturday's Grand Final against Hawthorn.

In contrast, Ellis played just 16 games in his final three seasons at the Hawks.

He was part of Hawthorn's 2008 premiership side, but injuries cruelled his chances of featuring in the 2013 flag.

And as his days at Hawthorn wound down, Ellis let himself go - adding 10kg to his 186cm frame in quick time.

"I was as fat as a house to be honest," Ellis recalled this week.

"I just hadn't been able to do a hell of a lot of running.

"I probably drank too many beers while I was out injured and watching the Hawks win the 2013 grand final.

"I remember just before I moved over to West Coast I split my suit at the Spring Carnival races.

"I think I had a couple too many drinks to think it was a light-bulb moment".

Ellis is now just one win away from becoming a premiership player at two different clubs.

The 27-year-old still has many good friends at the Hawks, with Matt Spangher, Liam Shiels, Matt Suckling, Grant Birchall, and Jarryd Roughead among the players he keeps in touch with.

But all niceties will be cast to the side this week as Ellis attempts to help West Coast win their first flag since 2006.

"I'll obviously be pretty anxious about the day," Ellis said.

"But I'm more nervous because Hawthorn are the best team of the past 10 years - arguably the greatest Hawthorn team of all time.

"We're underdogs. But we're a confident group of underdogs."

Ellis paid special tribute to Simpson for having the faith to bring him to West Coast.

Simpson was an assistant coach at Hawthorn for four years, and he knew the special qualities Ellis possessed if he could get fit.