As soon as news of the trade broke (via the Washington Post), many fans and experts, myself included, were thinking that Jaso, coming off a career year—a .302 batting average, .394 on-base percentage and 10 home runs in 294 at-bats over 108 games played—would be the everyday starter.
Now that the dust has settled and we have had time to look closer at Jaso, he is still an upgrade over George Kottaras, whom the A's designated for assignment to clear a roster spot for Jaso. However, he is not quite an everyday starter.
Dissecting Jaso's numbers from 2012, he hit .302 with all 10 home runs coming off of right-handed pitchers. Against lefties, his batting average tumbled drastically down to .119 and he had only three RBIs. His on-base percentage also dropped from .419 to .250 between righties and lefties.
With the aforementioned designation of Kottaras, the A's still have Jaso and Derek Norris as their two catchers, and it will likely stay that way, as the two can be expected to platoon due to the difference in success that Jaso has against right- and left-handed pitching.
As I said above, with the dust settled from the trade, we have all had more time to research Jaso. It is worth noting that he caught Felix Hernandez's perfect game as a Seattle Mariner.
He should help the A's behind the plate as the best game-caller since Kurt Suzuki was traded in 2012.