Siegal, a Cleveland native, wore a patch honoring Christina Taylor, the nine-year-old granddaughter of former major league manager Dallas Green, who was killed in last month's shootings in Tucson.
Siegal, 36, was the first woman to coach first base in men's professional baseball for the Brockton (Mass.) Rox, an independent league team, in 2009. She spent three years as the only female college baseball coach in the country, when she was an assistant coach at Springfield College (Mass.) from 2007-10.
Siegal, who throws right-handed, is scheduled to throw batting practice in the Oakland Athletics camp later this week.