One fan appeared to extend his left arm over the wall to snag the ball in his glove, but somewhat surprisingly, interference was not called. He and others in the section then greeted Mercado with finger wags and verbal taunts. One of the main rules of being a baseball fan in an MLB ballpark is not reaching onto the field to interfere with live action.Mets fans in the left-field corner of Citi Field disregarded that principle entirely Tuesday when Indians outfielder Oscar Mercado tried to run down a fly ball in foul territory. Unreal trolling from Mets fans.pic.twitter.com/PWQnZvsvU4— Sporting News MLB (@sn_mlb) August 21, 2019MORE: NL wild-card race breakdownWhile Phillies fans proudly wear their rough edges with pride and Braves fans tomahawk chop their way through 162-game seasons, this incident could give the Mets an edge in the annually tight NL East fan base villain race. The finger wags — and, dare we say, haircuts — from the entire section put the whole thing together.Mercado appeared to see the taunts, but he did not offer a visible reaction.