Brian McCann’s future with the Braves is certainly open to speculation, as Jerry Crasnick points out so effectively. And if McCann does wind up a free agent, a lot of potential earnings will be tied to two qualities: His bat and position scarcity, because catchers who can hit as well as McCann had before 2012 are rare.

Two things might get in the way of a big payday for McCann after 2013. As Jerry points out, after stumbling to a career-low .699 OPS in an injury-riddled 2012, McCann will be working to recapture his reputation as an offensive force. But the other half of his reputation is that he’s not the best defensive backstop around, certainly suffering from comparisons to contemporaries like Yadier Molina or Buster Posey.

Criticisms of McCann’s defense are fair if you limit your focus on McCann’s ability to throw out opposing basestealers. Major league caught-stealing rates during McCann’s career have hovered around 27 percent, and he’s delivered a below-average 24 percent, bettering the MLB average just once during his career (in 2010, with a 30 percent CS rate).

However, it’s important to remember that while McCann rates as a below-average thrower, the impact of the running game has declined. Last year, there was less than one stolen base attempt per game, at 0.9. Whatever impact McCann’s below-average throwing performance might have, it hasn’t encouraged opponents to run wild on the Braves: Opponents have averaged just 0.9 stolen base attempts per nine innings against McCann on his career, so if this is supposed to be a significant weakness in his game, they aren’t exploiting it. Which suggests that in the scope of a 162-game season, as problems go, this isn’t a big one.

Moreover, defining McCann’s value on defense only by his caught-stealing rate would be a mistake because it ignores McCann’s effectiveness at containing damage on loose balls around home plate. While the distinction between a passed ball and a wild pitch might be a near-nightly cause for debate in the press box, analyst Matt Klaasen has been tracking the impact of pitch blocking plays since 2008, and had McCann in the positive at 0.8 runs. FanGraphs has developed a runs metric for evaluating value blocking pitchers (RPP); they had McCann tied for fourth in the majors last year at 3.5 runs above average, outperforming the all-world reps of Matt Wieters (3.4) and Molina (2.0).

What about game-calling, another key component of catcher performance. Using a stat like Catcher ERA is problematic (opportunities for who you catch and who you’re catching against aren’t evenly distributed), but metrics like Baseball Info Solutions’ Catcher Pitch Calling Runs (or RerC) on Baseball-Reference.com suggest that McCann has more than held his own here as well, bouncing between plus-7 in 2008 to minus-6 in 2010, totting up to zero for his career so far. That isn’t great if you’re comparing him to “best catcher on the planet” candidates like Yadi (plus-12 career) or Wieters (plus-13), but it’s far from a serious handicap for a potential employer. In 2012, McCann was one of the few catchers who made a measurably positive impact (plus-3).

On some level, you also need to give McCann some credit because he’s going to suffer by direct comparison with a teammate. That’s because he was paired up with David Ross, a much better thrower. Ross nailed almost 40 percent of opponents’ stolen base attempts in his four years as a Brave, consistent with a 39 percent career clip. However, McCann has outperformed the highly regarded Ross in these other metrics: Ross rated negative as a plate blocker in 2012 (Klassen’s PBWPRuns have him at minus-0.7, FanGraphs at minus-1.6), and at minus-1 by BIS on pitch-calling. Not huge negatives, but notably worse than McCann.

What comes through with these smaller numbers is that they suggest how much we shouldn’t obsess about McCann’s performance as a receiver. This isn’t Olympic figure skating: The guy’s clearly playable, and the defensive impact of his limitations against the running game border on negligible. He’s not the best backstop in baseball, but he’s above average in some important areas of a catcher’s responsibility. If you want a receiver who gets the job done, you could certainly do much worse.

Christina Kahrl covers baseball for ESPN.com. You can follow her on Twitter.