No wonder they’re laughing

Did the Cleveland Indians’ players read this on the Yahoo! front page? Is that why they’re laughing?

In the United States, team names are treated as plurals, so it makes no sense to form the plural of a team name by adding an apostrophe and an S. If the name ends in an S, we just add an apostrophe. That’s what we do in the U.S., but the style may be different in the country where this was written.