When Anthony Rizzo, Kris Bryant and Kyle Schwarber connect at the plate, their exit velocity — the speed at which the ball leaves the bat — often exceeds 100 mph. A ball hit that hard travels 146 feet in about a second. And spectators sitting far closer to home plate than that are unprotected and virtually helpless. The netting at Chicago’s Wrigley Field extends only far enough to shield Cubs fans sitting within 70 feet. Netting at Guaranteed Rate Field, home of the White Sox, offers similar protection, in line with the current recommendations from Major League Baseball.