Neither provides much in the way of offense. ZIPS has the pair basically equal (Navarro with a four point edge) and they profile as similar hitters anyways. Navarro has the prospect lineage, the ability to switch hit, and at least one successful season behind him, but his plate approach has worsened with the leitmotif being an inability to lay off pitches outside of the strike zone. Hernandez is the same package without the niftiness and with a track record of being a mediocre minor leaguer.
Multiple times we've looked to see whether Hernandez handles the staff better and found traces but nothing definitive. At this point, if the Rays feel Hernandez truly offers better play defensively, or at least somewhat better play, then there is zero reason to play Navarro every day.
I'm not saying simply thinking a catcher is a great defender is reason enough to play him. Instead this is like the chemistry thing. If you have two players with completely equal quantifiable skills, but one is part of the local ministry and the other could be a werewolf, well, you probably go with the saint - unless you need some theatrics in which you go with Carl Everett.
Seriously, the .004 projected difference is worth 2 runs over 600 plate appearances. I'm not a Hernandez fan, but I don't think I can argue that Navarro should play every day.
Someone on the waiver wire has to be cheap and better than these two. Right?