There are some big differences though. Betts started 2014 in AA, not A. Betts was called up to a last place team. Betts also benefited greatly by the total ineptitude of Sox outfielders that year: JBJ imploded, Victorino was hurt most of the year, Gomes was traded and really didn't do much before he was, Nava was terrible the first half. There is not a comparable situation in Boston this season.
No need to rush the kid. Yes, if he keeps raking at Salem he'll be in Portland before the end of the year, but that will probably be it. He appears to be a keeper, but let's not ascribe Trout/Harper fly through the levels type talent to him.