What triggered this wild baseball scene?

The culprit, according to the wire photo caption, was Dodger pitcher Don Drysdale, who sent a fastball a bit too close to Johnny Logan's head.  Logan, who was ready to fight at the drop of a syllable, far left in the photo, has his arm cocked ready to smack Walter Alston, number 24 and manager of the Brooklyn Club, in the side of the head.  Meanwhile, Drysdale is being held, at the right of the photo, by an unknown Milwaukee Braves coach, wearing number 8.  In the upper portion of the mele Pee Wee Reese guides a tumbling Eddie Mathews on top of his teammate already on the ground.  This 1957 scene at Ebbets Field in Brooklyn was shocking; the outrage was palpable in the National League's front office.  The fines were stiff: Johnny Logan $100.  Don Drysdale $40.