Rosario is going to be the starter. Nobody is close enough the big leagues to usurp him from that role and the Rockies aren't going to explore the free-agent or trade markets to do so. And that's fine; sure, he's a mediocre defender behind the plate, but I'll take 20 home runs and a .275 batting average from my catcher any day of the week. Plus, at only 25 years old on Opening Day, there's still plenty of room for Rosario to grow as a receiver, particularly when you take into account the fact that he'll be working under catching genius Jerry Weinstein (who, if you can decode his tweets, is a must-follow on Twitter).
Dan Szymborski is mean and wouldn't tweet me back with a peek at Rosario's ZiPS projections for 2014, but logic says that, health permitting, Baby Bull should also see some offensive improvement. And that's great news about a guy who hit .292/.315/.486 with 21 homers as a 24-year-old.
In short, I'm not really worried about Rosario. I think the Rockies are set behind the plate for a number of years to come. That is, in the majority of their games; the days of catchers starting more than roughly 120 games behind the plate are pretty much gone, so a big key will be what happens in the other 40 to 50 contests.
That's where Pacheco comes in. Rosario's bat could still be in the lineup on those days, especially against left-handed starters. But having a guy who can give any sort of positive contribution with the bat would be a huge boost. Pacheco did not do that last year, but he's just a full season removed from having a solid (but unspectacular) year at the plate as a rookie, hitting .309/.341/.421.
I don't know how good of a catcher Pacheco is, but like Rosario, he's got time on his side and is learning from one of the best. But, I do know that any value that Pacheco has as a big-leaguer will come as a backstop. He's not particularly good with the glove at third or first (or second or the outfield -- you get the point), and he probably isn't going to hit enough to make up for that. But, if he's even an average catcher, there will be much worse options to run out there every fourth day or so.
I don't love Pacheco as a big-leaguer -- and I don't think he'll ever hit like he did as a rookie, mostly because he probably won't ever see that much playing time -- but I think the Rockies are making the best of their catching situation. Tom Murphy and Ryan Casteel are both another solid minor-league season away from getting a long, hard look by the major league club, and until that happens, the upper-organization depth can be filled by signing a veteran free-agent. as Renck mentions.
At this point, making Rosario and Pacheco at least feel a sense of competition in spring training is the best the Rockies can do, and it's the path they should take.
Troy Tulowitzki, as expected, was selected by fans as MLB Network's "Face of the Rockies." Check out the chain of tweets in response.