Gold Gloves are bunk. Let's talk about them anyway.
Baseball-Reference, because it has everything under the sun, has the lists of Gold Glove winners for the American and National leagues through history. Like other pages on B-Ref, it uses shading to indicate sequences and thus gives the user at-a-glance insight into how often the award at a given position changes hands. (It's also a feature of, inter alia, team defensive lineup pages, so that a position held on lockdown all year by one player is distinguished easily from a rotating cast or platoon situation.)
When you look at the shading of this year's Gold Glove winners, you'll notice just one repeat player in the National League and three in the American. Four out of 18 should not be a surprising number given league turnover and injury and skill erosion and ability whatever-the-antonym-of-erosion-is, but Gold Gloves are, at least to hear statheads tell it, decided on a variety of factors that only partially include actual defensive skill and more importantly deal with questions like "did dude win it last year?" (Or forget statheads — let's ask a labor economist.)
There have been two-league Gold Gloves since 1958. Here's a list of all the previous years in which there were four or fewer repeaters one year to the next: 2011. FIN.
One time! And that one time is cheating, too, because 2011 was the first year since 1959 that the outfield Gold Gloves were awarded to the three separate positions rather than for all outfielders as a lump. The 2010 NL Gold Glove outfield included both Shane Victorino and Michael Bourn, for instance, and thus 2011 had one nearly guaranteed spot of turnover. ("Nearly" because it's possible that either Victorino or Bourn could have moved to a corner for 2012, though that might typically suggest that the man was not worthy of a Gold Glove the previous year. Nor that unworthiness has ever stopped anyone before.)
I'm not going to quantify anything in this article, but let me explain the process by which I manually compiled the above list-of-one. I started with the page of National League winners and scrolled across in each year counting how many repeaters I saw. If the number was four or fewer, I would flip over to the American League page to continue the count for the year in question. If I got to five before even seeing the American League, then obviously I did not need to flip pages because I was already past four and you can't have negative repeaters.
I mention this because I sensed that I started having to flip over to the American League page far more often as time went on, with a particular shift occurring, I would guess, somewhere around the early 2000s. If you click those links above, I suspect you'll agree that, visually, the early 2000s appear much more checkerboard than the monochromatic 1970s. There are certainly still long streaks in modern times, like Greg Maddux, Andruw Jones, Jim Edmonds, Torii Hunter, Ichiro Suzuki, and Eric Chavez, but you also see four winners in the last four years for NL pitchers, first basemen, and third basemen, as well as AL second basemen. Note that free agency creating more league-switchers (if indeed that is true—players changed teams far more often pre-free-agency than "good old days" types like to admit) wouldn't seem to explain the shift because free agency came around far earlier than the early 2000s.
So why all the turnover? If talent and performance are more variable than reputation, it's possible that the managers and coaches who vote on the award are actually aware of or are being told about advanced defensive stats and are thus voting on different criteria than in the past. (Much as we might like them to vote based on their eyes, how hard was Joe Girardi really looking at Alex Gordon's defense in left field the seven times the Royals played the Yankees in 2012? Does it actually matter to him to evaluate Gordon's defense beyond preparation for the third-base coach's decisions about whether to send or hold runners? That is, does he have an incentive to judge enemy left fielders on their defense? And thus does he truly have a sense just from watching the two play a few times a year whether Gordon is better than David Murphy such that his vote can honestly be called "informed"?) It's also possible that the same rules and the same biases and the same shortcuts as ever have applied and it's just circumstance that's resulted in the record turnover of the last two seasons. A position-by-position glance (cough) at how the awards came to pass could be helpful.
Pitcher: Mark Buehrle won three in a row from 2009 to 2011 after Kenny Rogers and Mike Mussina loosened their stranglehold on the award by retiring after 2008. Buehrle abandoned the South Side for a Miami address in 2012, though, leaving AL voters in need of someone new. They copped out and split the award between Jeremy Hellickson and Jake Peavy. Lucky for us all, this doubles the chance (don't check my math on this) that next year's winner at the position is a repeater, especially since Peavy, who could have been a free agent, has signed a multi-year deal in Chicago.
Catcher: Joe Mauer was the reigning champion heading into 2011, but he played just 82 games and got only 47 starts at catcher that year. Matt Wieters took the award and ran with it again this season. He does have a sterling defensive reputation, but it took Mauer becoming a part-time catcher to give Wieters his shot.
First base: Mark Teixeira vs. Adrian Gonzalez in 2011 was a battle of incumbents, with Gonzalez entering the junior circuit after winning the award three years out of the previous four in the NL. Gonzalez won out, which is no real surprise given his visible smoothness and athleticism (would the Yankees put Teixeira in the outfield for interleague play?) and Teixeira generally looking like he has an entire lumberyard in his pants. Gonzalez was traded back to the NL in the middle of this year, though, so Teixeira regained his crown.
Second base: This is weird. Robinson Cano, Dustin Pedroia, and Placido Polanco have each won two awards in the last six years, but none of them were consecutive. If the pattern holds, an entirely new second baseman will win the award in 2013, followed by Pedroia in 2014, then our new Mr. X again in 2015. What do you say? Jurickson Profar? In any case, there does not appear to be any circumstantial rhyme or reason to much of this beyond Polanco leaving for the NL after his second award.
Third base: Adrian Beltre won in 2007 and 2008, then played just 111 games in 2009, allowing Evan Longoria to jump in. Longoria won for two years, but then both Beltre and Longoria played a short-ish schedule in 2011: 133 games and 124, respectively. On the one hand, Beltre missing time gave the voters the opportunity to apply incumbency rules because the two stood on relatively equal footing. On the other hand, Beltre had a batting average over 50 points higher. Beltre's repeat in 2012 doesn't do much to point one way or the other, though, because Longoria played just 74 games and American League third basemen with good defensive reps are in short supply these days. I mean, Brandon Inge managed only 83 games himself and he was a finalist for the thing.
Shortstop: Jeter-Aybar-Hardy is how this has gone the past three years. Maybe not voting for Jeter in 2011 is a sign that voters are waking up, but he did miss about 30 games. On the other hand, there are no playing time or batting reasons for Erick Aybar to have lost the award to J.J. Hardy this season—Hardy, in fact, had a horrible year with the stick. He likely benefited from the light reflecting off the Orioles' run to the playoffs, but Ryne Sandberg, to pick a name, won a lot of Gold Gloves on a lot of ugly Cubs teams in the '80s. This one seems like a legitimate decision that Hardy was a Hoover at short.
Right field: Nick Markakis got hurt this year, so Josh Reddick's Spider-Man routine and flashy, sexy, shiny, gorgeous, orgasmically beautiful arm (okay, Okay, OKAY, ugh) were allowed to step in and bring Oakland its first outfield Golden Leather since Dwayne Murphy in 1985.
Left field: After 2010, Carl Crawford moved to a team with a Green Monster and immediately commenced injuring himself and failing to hit. Alex Gordon stepped into the breach and stood ready to repeat in 2012, which he did.
Center field: Jacoby Ellsbury plays for Boston and thus missed much of 2012 with injury. Adam Jones took advantage. Next year's choice between Jones and Mike Trout (and here's to hoping that both stay healthy and play well enough to make that a genuine choice for the voters) may really put any conclusions regarding the tendencies of Gold Glove voters to the test. Trout is certainly a flashy defender, and both FRAA and the batted-ball metrics agree that Trout is better than Jones. Keep an eye on this one, friends!
Pitcher: Mark Buehrle moved leagues and stepped into a situation with no clear incumbent, as the prior three winners had been Adam Wainwright (I don't see any external reasons for him not to have repeated in 2010), Bronson Arroyo (who pitched horribly in 2011), and Clayton Kershaw (who might could have won in 2012 had Buehrle not walked in and started bossing everyone around like he does god he's so annoying).
Catcher: Yadier Molina is starting to look like Ivan Rodriguez (not literally) with five straight wins and no real end in sight given that he just had his age-29 season. Buster Posey's going to have to slug .700 to have a chance.
First base: Four winners in four years, and it's kind of weird. Adrian Gonzalez won in 2009, lost in 2010, then left the league for 2011. Albert Pujols won in 2010, lost in 2011, then left the league for 2012. Joey Votto won in 2011, lost in 2012, then [REDS FANS RUN SCREAMING INTO THE STREETS]
Sorry. The real problem was that Votto missed a lot of time and, as mentioned, the other recent choices, Pujols and Gonzalez, left the league. This spot presents another interesting scenario for 2013: does Adam LaRoche, assuming he stays in the NL, win again? Does Votto reclaim his crown with his health? Does Gonzalez become the de facto incumbent as a Dodger? Or do they split the vote and Susan Lucci breaks out as the surprise winner?
I can't make any argument that this award was anti-incumbent, but I would like to point out something: the thing that Barney did in 2012 is set a record for most consecutive games at second base without the official scorer giving him an error. It isn't clear to me how happy we nerds should feel. On the one hand, Barney likely was not given the award because of reputation (nobody knew his name before this year) or hitting (.305 career OBP, .299 this season), so in a sense, he was chosen for fielding. On the other hand, errorless streak. We all know how useless errors are. I'm scratching my head. Is this a step forward or a step back for defensive-award voting?
Third base: Scott Rolen won in 2010, then played 157 games combined over the next two years. Placido Polanco won in 2011 and then played 90 in 2012. I think it's fair to consider this position to have been sans incumbent. Consider also that winner Chase Headley broke out with a .498 slugging percentage (with half his games in Petco!) and was recognized as one of the best players in the game this year. As long as he's not a butcher in the field, that's exactly the kind of profile that winds up recognized with Yellow Handwear. (I'm really really running out of ways to describe the award without just saying "Gold Glove" over and over. Work with me.)
Shortstop: Jimmy Rollins won from 2007-09. Then he got hurt in 2010. Troy Tulowitzki won in 2010 and 2011. Then he got hurt in 2012. Rollins was waiting in the wings to take back what was rightfully his. (Note: I have no idea if it was rightfully his or not. Given that he is a professional ballplayer, I'm sure he considered it so.) As you've seen at this point, this is an archetypal Gold Glove story.
Left field: Carlos Gonzalez won an outfield award in 2010. Gerardo Parra won the left field award in 2011 as Gonzalez played just 61 games in left, with another 64 in right and center. Gonzalez became a full-time left-fielder this year, though, and was thus positioned to take back the award.
Center field: Matt Kemp won in 2011, then got hurt a lot this year. He's probably better suited to a corner anyway and probably won the 2011 honor based on his offensive work. Which was absurdly stellar. Anyway, in 2012, with Kemp hurt, Andrew McCutchen hit like an MVP candidate. Guess who won the Gold Glove. (It's not Andres Torres.)
Right field: Jason Heyward legitimately stole this from Andre Ethier, especially given their very similar slash lines at the plate. I don't see anything (other than defensive merit) stopping the voters from taking Ethier.
Are you still with me? Let's go back and do a tally. Of the 14 trophies that changed hands, I count four as having done so "legitimately"—American League second base and shortstop and National League second base and right field. I haven't proved a thing in my life since I quit doing math after college, but I think there's at least a suggestion here that the (un?)conventional wisdom regarding Gold Gloves, that they're based on hitting and fame and incumbency, is still very much true, and that we're looking at a fluke season or two of significant turnover being caused by a freak storm of rule changes (the shift in outfield awards), injuries (especially Mauer, Longoria, Tulowitzki), and league-switchers (Buehrle and Adrian Gonzalez in particular) more than by a shift in voting patterns.
It's also possible that managers are in fact using data provided by front office nerds to vote, or that they're smarter about how they vote with their eyes (not being fooled by tricks of the memory and flashy plays), but it's being masked by the narrative I've constructed above. Like I said, I can't prove anything, but I would suggest that this does not appear to be the most likely explanation for Gold Glove voting at this time.
So but hey, mazel tov to the winners one way or the other, and I hope they enjoy their bonuses.