Very unfortunate for the kid if that's how his teammates are treating him. A kid committed from my son's high school team last year and I don't recall him getting that sort of treatment at all. He was more or less the team hero already so that wasn't surprising to me.
Like it or not, it seems that we live in a society where people are measured by their achievements, for the most part, and those achievements are instantly available in this age of social media. Some kids will never have the work ethic, physical gifts, connections, and all other things that go into achieving on the baseball field and I think the reaction of the teammates in the original post is simply how young brains may be responding to that reality.