Still, several fans have been hurt by foul balls this season.
"We recognized early in this process that it was very difficult to set an individual rule, one rule that applied to 30 different ballparks given their structural differences, and instead we have opted to work with the individual clubs over a period of time to extend netting," Manfred said before Tuesday's All-Star Game.
"We've made extensive progress on that and I believe that that progress will continue, and I think one of the reasons that we have had progress is that we have not put clubs in an impossible position by adopting a one size fits all rule."
Manfred said changes during the midst of a season are hard to put in place.
"I don't think it's unreasonable to think that clubs are going to take a period of time figure out what they can and can't do structurally before they announce what their plans are going to be," he said. "One injury is too many, but the fact of the matter is that we know because of the number of balls that hit into those nets, we had less incidents than we used to have. We are better off than we were, and I do believe we will continue to make progress on it."
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