I took a look at the top ten in AL saves, and only Addison Reed looks like his team moved him into a closer's role without at least 100 IP in the majors. (Tom Wilhelmsen technically would be another but he was 28 when he started racking up major league saves.) I'd like to see a guy like Tonkin really get his feet under him at the top level before trying him in the ninth, unless he really forces the issue by being lights out for a period of time.