Teams usually like ther prospects to have at least 1,500 plate appearances before moving up to the majors. McGonigle has about 750 right now. A full year in AAA will probably put him around 1,200.
Reports I've read is that he has good enough feet and actions for SS, but not enough arm. Longenhagen thinks he will be an excellent 2b. Rainer looks like he has all the goods to be an excellent SS. Rainer really has a hose.