Even as MLB struggled to contain the chaos spawned by this week’s novel coronavirus outbreak among the Miami Marlins — which forced the postponement of 14 games and upended the schedules of six teams from the National League East and American League East — new cases among the St. Louis Cardinals on Friday created an additional crisis and raised new questions about the season’s viability amid a pandemic.

The Cardinals’ game Friday in Milwaukee, which was to be the Brewers’ home opener, was postponed, MLB announced, and will be made up as part of a doubleheader Sunday; the teams’ game scheduled for Saturday remained on as of Friday evening.

The rescheduling, MLB’s statement said, “is consistent with protocols to allow enough time for additional testing and contact tracing to be conducted.”

Still, that meant six teams, or 20 percent of the majors, sat idle Friday because of coronavirus-related postponements: the Cardinals, Brewers, Marlins, Philadelphia Phillies, Toronto Blue Jays and Washington Nationals. The St. Louis cases involve two players.

The Cardinals’ samples that produced the positive tests were taken Wednesday in Minneapolis, where St. Louis played the Minnesota Twins before a day off Thursday, according to a statement from the team. The statement said the team’s players and staff were instructed to “self-isolate in their Milwaukee hotel rooms until further notice.”

The team is “conducting rapid testing of the entire traveling party, has implemented contact tracing, and will continue to self-isolate,” the Cardinals said.

St. Louis General Manager John Mozeliak said the entire team underwent testing Friday, with the results expected early Saturday. If there are no additional positives, he said, the team would “feel very comfortable” playing as scheduled Saturday and Sunday.

“It’s obviously creating a lot of anxiety here,” Mozeliak said during a video interview with reporters.

Friday night’s Twins-Cleveland Indians game was played as scheduled; the Indians played at the Twins on Thursday night, using the same visitors’ clubhouse at Target Field that the Cardinals used the night before.

The Marlins remain baseball’s biggest concern, with another player testing positive Friday to increase the team’s total this week to 18 players and two coaches. Both the Marlins and Phillies — who hosted Miami for three games last weekend and have seen three staff members test positive in the days since — have been shut down since Sunday and will not play again until at least Monday.

MLB officials believe the Marlins’ cases probably were the result of poor decision-making and social distancing practices both on and off the field, and they have discussed, both internally and with the players’ union, the need for players and staff from all teams to tighten up those behaviors or risk jeopardizing the season.

“We’ve come so far to get to this point,” Los Angeles Dodgers Manager Dave Roberts said in a video interview with reporters, “and for it to be shut down because of people being irresponsible is certainly unacceptable.”

Following the Marlins’ outbreak, Commissioner Rob Manfred told MLB Network it was not a “nightmare” scenario, and the sport planned to move forward with tightened health and safety protocols and a makeup schedule likely to be packed with doubleheaders — which would feature seven-inning games under a new rule agreed to by MLB and the players’ union Thursday night.

“We built protocols anticipating that we would have positive tests at some point during the season,” Manfred said. “The protocols were built to allow us to play through those positives. We believe the protocols are adequate to keep our players safe.”

But multiple, separate outbreaks in different regions of the country could test the collective optimism over finishing the 2020 season. Until Friday, baseball had reported zero positive tests among players — outside the Marlins — since July 24.

With both the Marlins’ and Cardinals’ outbreaks apparently having occurred while on the road, the decision to contest a 60-game season with teams in their home markets and traveling between cities — a model that was questioned by many epidemiologists and health experts, who believed the bubble models used by the NBA, the WNBA and MLS had a better chance of succeeding — has come under renewed scrutiny.

MLB considered various bubble models in the early stages of planning for a 2020 season but met resistance from players over the notion of isolating for months at a time away from family members and ultimately decided it was too unwieldy to house 900 rostered players plus staff members — and contest an almost-every-day sport requiring numerous stadiums — within one or more bubbles.

MLB’s swift postponement of Friday’s Brewers-Cardinals game was also a tacit acknowledgment that the Marlins-Phillies game this past Sunday — which went forward despite the Marlins having reported four players testing positive by that point — should not have been played. Absent any guidance from MLB that day, Marlins players and staff discussed the wisdom of playing but said they never seriously considered not taking the field.

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