A few names come to mind when pondering the surefire Hall of Famers playing baseball today. Adrian Beltre, who recently broke the 3,000-hit barrier, is one, as is Mike Trout, despite his youth. But there’s another all-time great who is toiling away on one of the worst teams in MLB: San Francisco Giants catcher Buster Posey. The Giants’ record might make Posey easy to overlook, but his combination of hitting and defense makes him almost a lock to one day join the Hall. In fact, despite being only 30 years old, Posey might already have a Hall of Fame résumé if he retired today.It’s difficult to forecast whether any given catcher will find his way to Cooperstown. Only 18 backstops have made the Hall, and some did so in part because of accomplishments after their playing careers (as managers or executives).1For example, Rick Ferrell is listed by Baseball-Reference.com as having been inducted as a player, but he produced only 29.8 wins above replacement in his career (34th on the all-time list of catchers). However, Ferrell won two championships as an executive before his induction, which probably helped his Hall-of-Fame case. Perhaps because of the strain of constant crouching and the beatings they receive behind the plate, catchers are notoriously quick to decline, and historically great performers can become merely ordinary in the space of a few years.But Posey is special. In a nine-year career, he’s already amassed 37.5 wins above replacement (WAR),2According to Baseball Reference.com. which puts him 25th on the all-time list among backstops. If we look at how productive all catchers have been through age 303That is, up to and including a player’s age-30 season as defined by Baseball-Reference. — Posey’s current age — he looks even better, ranking 11th all-time in WAR.According to Jay Jaffe’s JAWS, a rough guide to measuring a player’s Hall-of-Fame qualifications,4JAWS (the “Jaffe WAR Score system”) determines Hall-worthiness by comparing an average of a player’s career WAR and his WAR in his seven best seasons with the typical mark for a Hall member at his position. Posey would have a decent chance to make the Hall even if he never played another game. I looked at the top 500 catchers’ JAWS scores and used them to calculate the probability that they would one day be inducted into the Hall.5I used a logistic regression model, with JAWS score as a predictor and Hall of Fame induction as the outcome. I excluded catchers who made the Hall as managers but not as players. Posey’s JAWS score is 36.8 — already only a little below the catcher average of 43.9. (Coincidentally, Posey’s current JAWS score is identical to the end-of-career score of stalwart backstop Ernie Lombardi, who made the Hall of Fame.) Based on this analysis, Posey would have about a 29 percent chance of getting to Cooperstown if he retired today — and as we’ll see below, those numbers probably understate Posey’s contributions.Why is Posey’s résumé so strong? It starts with his impressive numbers at the plate. Since 2009, Posey’s first season in MLB, he has the 17th-highest Weighted Runs Created Plus in baseball, and he’s the only full-time catcher in the top 50. Posey has power, to which his 128 home runs (in one of MLB’s least hitter-friendly ballparks) can attest. He also has patience, with a career walk rate of 9.6 percent, well above the MLB average of 8.1 percent.But Posey is much more than just a catcher who hits well. In addition to his power and discipline, Posey has been one of the best defensive catchers in baseball during his career — thanks to his particular knack for pitch framing.Catcher framing is the art of receiving a pitch so that an umpire is more likely to call it a strike. Before the debut of pitch-tracking technology such as PITCHf/x and Statcast, the idea of framing as a skill was unproven, but now it can be measured. And as Hall-of-Fame voters increasingly understand and recognize the importance of framing, catchers like Posey will probably benefit.Baseball Prospectus rates Posey as the seventh-best framer since 1988,6That’s the first year for which those statistics can be calculated. so he’s among the cream of the crop. And because framing isn’t factored into most versions of wins above replacement, Posey is somewhat underrated even by newfangled Hall-of-Fame yardsticks like JAWS.Baseball Prospectus’s version of WAR incorporates the number of runs a catcher saves via framing (which the version from FanGraphs does not, and the version from Baseball-Reference accounts for in a much smaller way).7The Baseball-Reference metric for catcher defense has a much smaller range of framing values than Baseball Prospectus’s does. For instance, it assigns Posey only 54 runs of value from his defense over the course of his career, while BP puts the value from Posey’s framing alone at nearly double that (104 runs). Unsurprisingly, Posey’s value under that measure is higher, shooting up to 49.8 WAR. If we recalculate his JAWS score using Prospectus’s version of WAR, then, Posey is already good enough to have an 85 percent chance of making the Hall, according to my calculations. Now, Posey’s framing value this year has been minimal, so it’s possible that he’s losing his touch (he wouldn’t be the only older catcher to forget how to frame a pitch). But even if you assume that he will be a league-average framer going forward, Posey’s JAWS could end up high enough to practically guarantee a Hall of Fame induction.8This is based on a series of career simulations described later in the article.In some ways, comparing Posey with the historic greats of yesteryear in this manner isn’t fair. We don’t know what kind of framer Johnny Bench was, for example, and it’s possible that his already-tremendous WAR total would just get more inflated if we did. But we do know that it’s rare for a catcher to have both offensive ability and framing skills. (The few catchers better than Posey defensively tend to be specialists like Jose Molina and Brad Ausmus.) Conversely, there are a lot of catchers who are not great framers but nonetheless have long careers because they excel at the plate. So it’s likely that at least some of the catchers ahead of Posey on the all-time list would see their total value decline if we could measure their framing ability.Add it all up, and Posey has likely already had a Hall-of-Fame career. And his playing days probably won’t end anytime soon — the average catcher who had 20 or more WAR through age 30 ended up playing another six and a half seasons. So Posey has plenty of years to improve upon his already impressive career. To get a sense of how Posey might end up finishing his run, I asked the folks at Out of the Park Baseball — a baseball simulation engine — to game out the rest of his career. Out of the Park came back with four simulations of Posey’s future. And according to each, the hypothetical Busters fared very well. In each simulation, Posey earned an end-of-career JAWS score of greater than 51, which would give him at least a 90 percent chance of making the Hall, according to my calculations. With an average of about 2,000 hits, 400 doubles and 250 home runs, Posey’s milestones weren’t overly impressive, so he didn’t make the Hall on the first ballot in the simulations — it usually took three to four years for him to get in — but he was eventually inducted in each universe that was played out. That sounds pretty similar to what will happen in our universe, too.Posey is one of the few catchers in history who can do it all. He can hit and frame, and he even provides extra value by blocking errant pitches and throwing out runners. When you combine his offensive and defensive skills, Posey might just be the most underappreciated Hall of Famer playing today.CORRECTION (Aug. 24, 10:02 a.m.): An earlier version of this article incorrectly said that Baseball-Reference.com’s version of wins above replacement does not incorporate the number of runs saved via catcher framing. It does, although Baseball-Reference’s method assigns less value to framing than Baseball Prospectus’s version of WAR does.