Here are the unplayed correct answers for this question!
Toronto Blue Jays
Baltimore Orioles
Milwaukee Brewers (we miss you SHOE!)
Pittsburgh Pirates
St. Louis Cardinals
Los Angeles Angels
This is off the top of of my head, but I think the Orioles are something like 8-0 or 9-1 over their last decade of Opening Day starts
And nobody stepped on the Yankees or Dodgers land mines for this question