Similarity scores were a terrific invention by Bill James. Essentially, every two players start at 1000 and get points deducted for the differences between the basic counting numbers. The concept was simple. If you want to know if a player is a Hall of Famer then you look at who they are similar to. If they are similar to Hall of Famers then they are probably a Hall of Famer. If the players they are similar to are on the outside looking in then they probably should be too.

Unfortunately, no system is perfect and the similarity scores aren’t either. They use basic counting numbers, so there is no allowance for the era the player played in or how long he had to amass those numbers. So, let’s take the aforementioned Harold Baines. He was most similar to Tony Perez. The similarity scores drop precipitously from there, but we also see the likes of Al Kaline, Dave Parker, Billy Williams, and Andre Dawson in the top five. Four of the five are Hall of Famers. So, as the story goes, Baines should be in the Hall of Fame.

Immediately, some of you are screaming at your computer screen and I’m right there with you. All of those guys were superior players. This is one of the reasons why I wrote The Hall of Fame Index Part II to begin with. The index serves a similar capacity as similarity scores, but since we are using different metrics we get a more representative comparison. Of course, it isn’t enough to just look at the index scores, so we are going to compare the best active player at each position to two similar players historically. The concept will be the same.

Career Value

Keep in mind that peak value gives us that element of dimension that is often missing when looking at a player’s overall career. Hartnett was productive well into his late thirties. So, his career had a certain longevity that we didn’t see with Posada and have not seen with Posey. Posey barely qualified for the index this past season. So, his career and peak values will be nearly identical. We also have not seen the offensive or defensive numbers.

Catcher defense is one of the more volatile elements in sabermetrics. We have seen a tremendous amount of growth in our understanding of catcher value. Obviously, Posey will benefit more from this than his predecessors. This will particularly true with total zone runs. For Posey, that will become defensive runs saved. That includes a heavy dose of pitch framing runs. We have some data on Posada (it isn’t pretty) and virtually none on Hartnett.

Peak Value

One of the things I explored in the book was the proclivity of great teams throughout history to have good catchers. It just seems to be one of those positions where it is rarer to have a really good one. If you have one you are more likely to be great. Posada’s Yankees won several World Series titles and Posey’s Giants have won three. Hartnett never won one, but his Cubs did end up going to the World Series.

As we have seen, 300 is the general standard for Hall of Famers, but that largely depends on the position. Neither Hartnett nor Mickey Cochrane reached 300 index wins, but no one would question their credentials. The index has no hard rules. It’s more of a comparative tool. We also include other tests. This time we will be added playoff performance to our tests to give us offense, fielding, playoff performance, and BWAR MVP points.

Offensive Numbers

We should keep in mind that Posey only has ten full seasons to his credit. He is just beginning the decline phase of his career. So, let’s say he becomes an average performer overall over the last three or four years of his career. He will still carry value and will likely pass Hartnett in the index, but the numbers here will definitely not look as good as they do now. So, the likely result is that he won’t look as good as offensively as the other two.

Hartnett’s numbers may appear to jump off the page, but we also have to remember that he played in the 1920s and 1930s when offense was at its peak in the 20^th century. Posada has a slight advantage over Posey as the 1990s and early 2000s were better for offense than the current time. This is why we tend to focus more on statistics like OPS+ and OW%.

Fielding Numbers

Posey gets a ton of extra credit for his pitch framing. It is clearly one of the dilemmas the Giants have dealt with in recent seasons. He is a brilliant defensive catcher when all things are considered. On the flip side, his offense is clearly declining because of the physical demands of the position. The Twins made the call to move Joe Mauer to first and they might have regretted it. Keeping him behind might cut his career by a couple of seasons, but it might be where he is most valuable.

Hartnett is clearly one of the gold standards at the position, but unfortunately we don’t know anything about pitch framing. Posada would have been better off if we didn’t know anything. His defense is probably what is keeping him out of Cooperstown. Still, as you can see with defensive win shares, he still has some value defensively.

Playoff Numbers

Playoff numbers serve as a tiebreaker. The problem with tiebreakers is that people put too much stock in it. It’s like the debate between tangibles and intangibles. Intangibles are often things we haven’t figured out how to measure yet. They have value, but people often discount the tangibles and go straight to intangibles. The playoff numbers don’t look particularly good for anyone here, but you are facing better pitching than you do in the regular season.

We often overlook numbers and look at how the teams fared. The Giants and Yankees won multiple championships while these players played for them. That might end up trumping the basic counting numbers you see above. Hartnett only got a couple of opportunities, so he obviously didn’t fare as well. Posada’s place on the best team in the last thirty years hasn’t helped him on the ballot, so Posey likely won’t see a bump here either.

BWAR MVP Points

One of the things we discovered in the book was the catchers often got more votes than the deserved in the MVP race. Hartnett won an MVP award when he clearly did not deserve it. Posada added a top ten finish when he probably did not deserve that. Hartnett and Posey fare better because they combine offense and defense in way Posada never did.

Based on all of these numbers we would have to surmise that Posey should be a Hall of Famer when all is said and done. He just needs a couple of average seasons to reach Hartnett’s total index score. You can see he is already superior to him in terms of offense, fielding, and the MVP points. None of the top four catchers on his similarity scores are in the Hall of Fame, but as we have seen, we have to look a little deeper.