Jeffers has 22 PAs against LH pitching this year, Vazquez 13. Neither has has many PAs.
And Vazquez has hit .167/.154/.167. for a .321 OPS in those 13.
Jeffers has a .697 OPS in his 22 PAs against lefties. .978 vs RH pitching.
Facing LH pitching hasn't been any kind of advantage to date. In fact it's hurt both, and Vazquez has been putrid.
Even up the playing time for a month and see what that looks like. For the record starters have done just fine with both catchers.
I believe the team is 2 games over .500 when Jeffers starts, 3 over when Vazquez starts.