Purina products are really not good at all. If you go to the this site:
www.dogfoodanalysis.com look for 4 or 5 star foods for Yorkies. Six stars are the best but sometimes they are too rich or high in protein for Yorkies (especially since Yorkies are prone to liver problems). There are a couple with lower protein in the six star section (Innova for one I believe), so that would be good.
Some foods that Yorkie owners here like are:
Orijen (extremely high in protein)
Innova
Innova Evo
Canidae (this seems to be the favorite)
Merrick
Life's Abundance
Solid Gold
Natural Balance'
A few of these are All Life Stages and the ones that aren't should have a puppy formula.