From May 6, when Leon started improving with the bat, until July 7, the last game before Vaz went on the DL, Leon's slash line was .322/.362/.529/.890. Granted, that was with an unsustainable .414 BABIP.
Since Vaz went on the DL, which is July 8, to the present, Leon's slash line is .118/.211/.147/.358. Granted, that is also with an unsustainable .182 BABIP, and both are small sample sizes.
The difference in performance might not have anything to do with Leon catching more games so far (he caught 5 days in a row and 7 out of 8 days), but as the season and postseason wear on, it's bound to have an impact.