"I went the free agency route so I had another year of junior eligibility and I thought I'd use that for my development," said Mantha.
The right-shooting defenceman wasn't comfortable signing the contract from the Rangers. Instead, he chose to remain with the IceDogs and learn under Head Coach Dave Bell.
"I just didn't like the contract," said Mantha. "I knew coming back that I'd have every opportunity to be successful, especially with coach Dave Bell jumping in as the head coach here."
The Oilers had begun scouting Mantha at the beginning of this season. That's when the dialogue first started.
"We're happy he signed with us," said Oilers President of Hockey Operations and General Manager Peter Chiarelli Wednesday.
Mantha was impressed with the way the Oilers approached him as well as the way they handled their young prospects this season. It played a part in his final decision to join the Oilers organization.
"I liked the approach they handled everything with," he said. "I thought it was very professional and very classy so that had a lot to do with it."
Mantha has 14 goals and 51 points in 58 games this season with Niagara. He describes himself as a big, steady defenceman that can make a solid first pass but plays defence first. For a taller skater, he's mobile and can fire it from the point.
"Ryan is a big right-shot d man that's a little bit of a late bloomer," said Chiarelli. "We scouted him, he's really had a strong year and he's a good prospect."
As of now, Mantha will continue playing with his IceDogs in an effort to push for an Ontario Hockey League playoff spot. After the OHL season, he could join the Bakersfield Condors.
"He'll be playing in Bakersfield, probably at the end of the year," said Chiarelli.
Mantha is just happy to become part of the Oilers organization.
"I'm pretty honoured and excited," he said. "I think the opportunity's going to be great for me."