We're not exactly overburdened with offense at the catching position so it comes down to defense and who the pitchers are more comfortable with. IMO Vaz is still the best defensive catcher on the team but I'm still going home with the girl who got me to the dance. The pitchers know him, he knows them, and it appears that there's a certain amount of comfort there.
However, remember, in 2013 Farrell didn't hesitate to make a catching change when Salty wasn't getting it done behind the plate, so anything can happen.