getting into a top tier or middle tier fraternity

Being a transfer junior won't have as big of an impact on getting a bid as whether or not you're a gigantic goober.

The bigger question is if you really want to spend your junior year with a freshman pledge class instead of going out to the bars. You will also be the one your pledge bros (and some actives) call on to go buy alcohol for them. Plus you will be hazed by actives who are younger than you. Does that sound like fun to you?

Anyway if you're so fixated on joining a good fraternity why didn't you rush in your first two years at your previous school? That gives us kind of a big hint on how big of a dweeb you are IMO.