The Eagles' favourite son was one of the favourites to fill the vacant position but was beaten by Hawthorn assistant Adam Simpson.
Simpson signed a three-year deal with the club on Thursday evening.
After failing to secure senior coaching positions at Essendon and Richmond, Sumich told radio station 6PR he was upset that he was overlooked by West Coast.
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However, he was excited for his future at Fremantle, he said.
"I'm gutted, no doubt about that," he said.
"I thought I was a really good chance of getting this one and unfortunately it didn't work out.
"I went for the Essendon job and Richmond and I was very close to [getting] the Essendon job … I've really been calculated in watching what I do with going for jobs and not going for too many.
"I got down to the last two, just like Essendon, and just missed out.
"But I understand the club's move and we all move on. I've just signed a new contract with Fremantle and I'm looking forward to that."
Sumich said he still wanted to be a senior AFL coach.
But he said he wouldn't apply for just any vacancy that came up.
He'd have to feel as though he was right in the running before putting his hand up again.
"It's still a burning ambition … but I'm at a great club now and hopefully I can be there for the long term but if it doesn't work out for me to be a senior coach, I'm not going to cry over that," he said.
"I've still got the ambition but I've got to be a bit picky and choosey and that's what I have been doing.
"I just can't keep going for every job. You've got to go for them when you're right at the death knock to get them, which I was again."
While Sumich said he could understand West Coast's decision to go with a coach without any ties to the club, he threw a little jab at its board, claiming it concerned him when non-football people made football decisions.
"The board were thinking a little bit differently to a lot of people and they make those decisions - I just worry about when boards make decisions, especially if there's not too many footy people on them," he said.
"The board's probably thinking they did need a fresh start with somebody away from the West Coast Eagles' brand and I've been there for a while as a player and a coach.
"Which is fair enough, like I said I love the club … they’ve been good to me but I've got to move on quickly because I know Fremantle are going places."
Twitter: @AFL_Harry
However, he was excited for his future at Fremantle, he said.
"I'm gutted, no doubt about that," he said.
"I thought I was a really good chance of getting this one and unfortunately it didn't work out.
"I went for the Essendon job and Richmond and I was very close to [getting] the Essendon job … I've really been calculated in watching what I do with going for jobs and not going for too many.
"I got down to the last two, just like Essendon, and just missed out.
"But I understand the club's move and we all move on. I've just signed a new contract with Fremantle and I'm looking forward to that."
Sumich said he still wanted to be a senior AFL coach.
But he said he wouldn't apply for just any vacancy that came up.
He'd have to feel as though he was right in the running before putting his hand up again.
"It's still a burning ambition … but I'm at a great club now and hopefully I can be there for the long term but if it doesn't work out for me to be a senior coach, I'm not going to cry over that," he said.
"I've still got the ambition but I've got to be a bit picky and choosey and that's what I have been doing.
"I just can't keep going for every job. You've got to go for them when you're right at the death knock to get them, which I was again."
While Sumich said he could understand West Coast's decision to go with a coach without any ties to the club, he threw a little jab at its board, claiming it concerned him when non-football people made football decisions.
"The board were thinking a little bit differently to a lot of people and they make those decisions - I just worry about when boards make decisions, especially if there's not too many footy people on them," he said.
"The board's probably thinking they did need a fresh start with somebody away from the West Coast Eagles' brand and I've been there for a while as a player and a coach.
"Which is fair enough, like I said I love the club … they’ve been good to me but I've got to move on quickly because I know Fremantle are going places."
Twitter: @AFL_Harry
