In MLB LIVE, 1. you need to have a minor league spot cleared BEFORE you place the bid, and 2. the PC player must go to your minors first, then be promoted in a separate transactions post.
In major leaguer baseball if you have an ERA north of 9 you wont win many games. You have to out hit your opponent. Thats what i had to do. But two teams fielded and ran bases better than me.