Over Rentaria (DET), would any of these players be viewed as an upgrade?

I think Guzman would be the best out of those if you want consistency. But if you want a hot player right now, Aviles is a better choice. Peralta has lots of homers, but not much else. Keppinger is a contact hitter, so he won't have many homers or rbi's. Guzman is kind of like Keppinger, but will score lots of runs. Aviles is having an awesome debut, but don't count on him to keep it up. Get Aviles for now, when he's doing better than Renteria, then get Guzman when Aviles is struggling, because rookies struggle longer than veterans.