Is Buster Posey already an all-time great?

I was driving around the other day, listening to MLB Network Radio and hoping the thaw of winter had turned to an early spring, when a listener called in and asked, "Is Buster Posey already an all-time great catcher?"

The host replied with a "Yes ... but" answer and pointed to Joe Mauer, who had three batting titles by age 26 and was a career .323 hitter with an MVP Award and three Gold Gloves by age 30, as an example of how a player's career can go south as he moves out of his prime years. Mauer, who was moved to first base in 2014 after a concussion ended his 2013 season in August, hasn't hit as well the past two seasons. Hall of Fame talk about Mauer, who was once viewed as a lock for Cooperstown, has subsided.

Posey is at the peak of his abilities right now. He is clearly the best catcher in the game, given the decline of Yadier Molina, and he is already the owner of three World Series rings won with the San Francisco Giants. In an era when hitters increasingly sell out batting average for power at the expense of more strikeouts, Posey is an old-school hitting machine who sprays line drives all over the place and walked more than he struck out in 2015. Here are two graphics that testify to his prowess at the plate:

Posey's home run power is to the pull field, but Posey has learned to take advantage of the bigger dimensions in AT&T Park’s spacious right field to spray his doubles and base hits. Check out the grid of his batting average. He has one little hole low and in; otherwise, he covers the entire plate as well as any hitter in baseball.

Back to the original question. Posey is entering his age-29 season. Where does he rank? By one measure, Posey is certainly on a potential Hall of Fame path. Here are the career WAR totals through age 28 for post-World War II Hall of Fame catchers:

Johnny Bench: 54.4

Gary Carter: 41.0

Mike Piazza: 31.0

Buster Posey: 28.8

Yogi Berra: 27.1

Carlton Fisk: 21.9

Roy Campanella: 10.2

Yes, the Hall of Fame has added only six catchers in six decades; the voters are tough. Campanella is a special case. He didn't reach the majors until he was 26 because of the color barrier, but Posey has outperformed Berra and Fisk, at least by this metric. Keep in mind, however, that these aren't the highest-rated players from this period; Ivan Rodriguez ranks second in WAR, while Joe Torre and Ted Simmons rank fourth and fifth, respectively. Joe Mauer is sixth, with 34.6 WAR through age 28, so as good as Posey has been, Mauer was perhaps even better.

Posey's numbers, however, are impressive, considering they've come in basically five seasons of games: his partial-year rookie season, his injury-shortened sophomore season and the next four full ones. Projecting forward, what would Posey have to accomplish to have not just a Hall of Fame-caliber peak but also a Hall of Fame career?

Voters have drawn a line, of sorts. The top six catchers in WAR since World War II are the five Hall of Famers (minus Campanella) plus Rodriguez. The gap from No. 6 (Berra at 59.4 WAR) to No. 7 (Simmons at 50.1 WAR) is sizable.

That means Posey is about 30 WAR short of Hall of Fame standards. In the past four seasons, he has averaged 5.9 WAR per season, and he was at 6.1 in 2015. A reasonable path of production would be 6.0, 5.5, 4.5 and 4.0 over the next four years. That's 20 WAR and takes him up to 48.8 through age 32 ... which is 1 WAR more than Joe Mauer is sitting on right now through that age. It would seem that Posey's Hall of Fame case might rest on his ability to remain behind the plate and put up solid numbers through at least his mid-30s.

Of course, Posey has those rings to show off, and that's an important part of his legacy. Since World War II, only Berra, with eight, and John Roseboro, with three, have won as many World Series as a starting catcher as Buster Posey (Jorge Posada caught for four championship teams with the Yankees, but Joe Girardi was the regular backstop during two of those runs).

Some have speculated that the Giants will eventually move Posey to first base, so as to have him avoid the injury risk of playing catcher and keep his bat in the lineup. I don't think there's a need to make that move yet. For starters, Posey is enormously valuable when he catches, with his offensive production and terrific defense. He has been above the league average in throwing out baserunners each season of his career, he rates well on pitches in the dirt, and he has guided his staffs to three titles. Why would the Giants want to remove that player from that position? They're certainly better off with Posey catching and Brandon Belt at first base than with Posey at first and Andrew Susac or somebody else catching.

The Giants have been pretty conservative with Posey's workload as well. He has started just 109 and 103 games at catcher the past two seasons, while mixing in 30-plus starts at first base and a few at DH, so he still played 150 games in 2015. That seems like a smart approach to keep Posey's legs fresh into his 30s. The move-him-to-first-base crowd will bring up Bench and his decline in his early 30s, but Bench caught an insane number of games early in his career. Through age 28, he had started 1,175 games behind the plate in the majors, compared to Posey's 562. Fisk, who played into his 40s, had started just 492 games due to some injury issues. I think the relatively few games he has caught will help Posey age well.

Anyway, we can speculate on when the Giants will make that move and whether Posey will end up in Cooperstown. For now, the Giants are lucky to have baseball's best catcher gunning for his fourth World Series title, and we're lucky to watch him do his thing.