When I saw the news of Oakland acquiring John Jaso, my first reaction was something like a big hearty "meh."
After giving it further thought however, I came to realize that this deal ultimately might not be great for any of the involved teams. More specifically, I failed to understand why Oakland would give up A.J. Cole for John Jaso.
Don't get me wrong, Jaso was awesome in 2012 and that should not be understated, but I just wonder if Jaso is going to be able to repeat his 2012 performance. The problem I have is that the A's had incumbent lefty-platoon partner George Kottaras, who despite not being the caliber of player Jaso is, is more than capable of providing value in that role.
Jaso posted a 143 wRC+ in 361 PAs in 2012, which is high, but not obscenely higher than his career wRC+ of 116. Jaso has shown some pretty sharp platoon splits in the majors, but as Matthew pointed out, that may be a small sample-size mirage. If that is the case and Jaso can play everyday, then Oakland has a steal on their hands.
Operating under the assumption that there is good reason that Jaso has not been allowed to accrue a large amount of plate appearances versus lefties, so for the purpose of this article we will view him as a platoon player.
The A's, as I mentioned previously, already had George Kottaras, a similar platoon catcher who has a career wRC+ of 97, but has posted 110 and 114 wRC+ in 2011 and 2012 respectively. Defensive metrics to not like either catcher's body of work behind the plate, which may be another fault in both players.
Jaso is certainly a better player than Kottaras, but I challenge just how much extra value Jaso will provide considering that both of them will have limited plate appearances due to their roles as platoon players. If Jaso is used in a full-time role and can indeed hit lefties as well as righties, then this trade will be a huge steal for Oakland.
Jaso's most likely outcome if he were to receive an increased role would probably be something resembling the 115 wRC+ he posted over 404 plate appearances in 2010 with the Rays.
It is also worth noting however, that the A's surrendered pitching prospect A.J. Cole in the deal, who is highly thought-of in some circles.
In their 2012 Prospect Handbook, Baseball America ranked Cole as the Nationals 4th best prospect going into the season (before the trade), and said he had potential to be a 2-starter who throws his fastball 90-98, with developing secondary pitches.
The young right-hander struggled in High-A for Oakland this year, before being sent down to Low-A where he finished the season strong. He has a decent shot to surface in the Majors as a reliever at worst, with the outside chance of becoming a 2-starter. Oakland also surrendered a decent relief prospect, but Cole was the main sacrifice.
To summarize: While Jaso is an upgrade (and potentially if things break right a huge one), I'm not sure that the chances of him being a large enough one to offset giving up a solid pitching prospect like Cole are particularly good.