Greg Swindell -- a former MLB pitcher who helped the Diamondbacks win the 2001 World Series -- is pleading for the public's help ... after he says his daughter has gone missing.
The 59-year-old wrote in a Facebook post over the weekend that Brenna Swindell, a single mom of three, went missing from the Austin, Texas area last Thursday -- and he and his family are worried sick about her.
Greg says her phone's been turned off and she has not been in contact with any one of her Swindell relatives -- including her own children.