One consideration was to bring up left-handed prospect Everett Teaford.
"The only other guy for me now would have been Teaford, and he's in the 'pen now," Yost said. "I could've brought Teaford up, but against these guys here, you look at their lefty matchups, and even their left-handed hitters are all pretty good against left-handed pitching."
Because of Monday's open date, Yost could've moved Sean O'Sullivan into Bruce Chen's starting spot on Wednesday night, moved up his other starters and brought up another starter from the Minor Leagues to move into the rotation in three days. That could've meant a promotion for a hot prospect like Danny Duffy or Mike Montgomery from Triple-A Omaha.
But not so fast.
"We have to make sure that when these kids get here, they are absolutely ready, and we're not quite ready with these kids yet," Yost said. "They're doing fine, but we're not quite there yet with these kids."
Yost pointed out that Mazzaro has big league experience, was 6-8 last year for Oakland and was already on the 40-man roster, which Duffy and Montgomery are not.