The Rockies have an odd habit of not playing Chris Iannetta anywhere near as much as they should, and they took that oddity to the next level by demoting him to Triple-A. Iannetta is currently hitting .133/.235/.333 over 34 plate appearances and eight games, so the Rox did not even give him the chance to rebound–or, to be honest about it, give him the chance to slump. We're talking about a little over a week's worth of playing time total.
Iannetta signed a contract for $8.3 million over three years this winter, which, given his track record and the fact that Miguel Olivo was signed for fewer years and less money (though $250,000 more in 2010) would make you think that he had a good handle on the starting job. That hasn't been the case though, with Olivo appearing in 12 games and racking up 47 plate appearances as well as a line of .311/.340/.667 in 2010. Iannetta was ranked as a four-star catcher prior to the season–despite low batting averages, he has more power than all but a handful of catchers in the league, and unlike his equally powerful teammate Olivo, can actually get on base without making contact.
Owners of Iannetta should sit tight–he is far too good to give up on, and Olivo is not going to hit like Albert Pujols all season long. Iannetta hit .264/.390/.505 in 2008 and .228/.344/.460 in 2009 (ISO of .240 and .232), and was projected to hit .263/.363/.496 for his weighted mean this year–his 30th and 20th percentile forecasts don't look so bad either, with ISOs in the .200 range. This is nothing more than a poor week at the plate for Iannetta, and the Rockies deciding that Miguel Olivo is their go-to catcher for the short-term because of it. Dropping him or dealing him would not be the best idea right now, especially given that this demotion has put a dent in his present-day value.
As for Olivo, he's not going to keep an on-base percentage that lofty (or a .300 average, for that matter) but the already homer-happy backstop is playing his home games in Colorado, meaning there's a good chance that he's going to produce for you while he is the starter. He's likely already off of the boards in NL-only leagues (or even some mixed leagues with two catchers), but he's a worthwhile option until Iannetta is given the vote of confidence by the Rockies again. If you had him on your team already, now is the time to play him–Paul Phillips is being called up to take Iannetta's roster spot, and though he hit well last year, it was in 54 plate appearances. He's not worth a look, and just clinches the idea that Olivo's playing time is going to increase.