Home-plate umpire Chad Fairchild called Cain out for interfering with catcher Bryan Holaday's throw on Nori Aoki's dash to second base in the eighth inning of Friday night's 2-1 loss to Detroit.
Yost thought Holaday got his throw to second base away before Cain got in front of him. The ball sailed past second base and Aoki reached third.
"I've seen that play called interference, I've seen that play not called interference," Yost said. "The umpires always fall back on 'in my judgment.'"
Although contact between catcher and batter is not necessary by rule for interference to be called, Yost views that as almost essential.
"They won't call it, generally, unless you make contact. As catchers we were always taught, just run right into him and throw the ball in the ground," Yost said. "Make it real obvious that you ran into him, even though you could still make a throw."
At any rate, Cain was called out and Aoki had to return to first base from third. The inning ended without the Royals scoring.
"The angle I saw it was hard to see if he made contact," Yost said. "In the umpire's judgment, it was interference."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.