You keep saying this, and people keep responding in the same way. fWAR is usually a good quick and dirty measure of what a player can bring to the table, but there is reason to believe that for catchers the number isn't of much use at all because it don't account for framing.
Navarro in his career has been worth about 1 fWAR per 500 plate appearances. He's been better recently so his projection is going to be a bit better than that (Steamer has him at 1.4). He's a bad athlete with a league-average bat and no significant platoon split, so you don't want him anywhere but catcher (including DH). So without any reason to believe otherwise, you have what should be a ~1.4 win player in 2015.
Now, there are four pretty good sources of information on pitch framing. They are as follows:
Matt Carruth's statcorner has Navarro -8.2 runs per 8000 chances from 2007-2014
Mike Fast's study -6.1 runs/8000 from 2007-2011
BP's framing report -8.0 runs/8000 from 2008-2014
JFaS, who's exact numbers escape me, but thinks he's one of the worst framers in baseball
So the best guess we have is that you take a ~1.4 win projection and cut about 8 runs off of it. So you have a player that you'd expect to provide you with about 0.5 wins over 500 plate appearances while earning $5 million. And it might be worse than that: Carruth had him at -20/8000 in 2014, BP had him at -11, and IIRC JFaS had him in the -20 range.
Sure, there might be a team that A) needs a catcher and can add one at $5 million and thinks Navarro is worth giving up an actual asset for, but you're counting on incompetency from any possible trade partner in that case.