An (Re)Introduction to JAWS: The Formula to Help Determine Who Should Make the Hall of Fame

Now that the 2018 Hall of Fame ballot has been released, it's time you re-familiarize yourself with JAWS, the formula that best determines who should be in and who should not.

The Baseball Writers' Association of America released their 2018 Hall of Fame ballot on November 20, featuring 19 newcomers—headlined by Chipper Jones and Jim Thome, but with several others worthy of consideration—and 14 holdovers. For the 15th year in a row, I’ll be evaluating each candidate’s career through a combination of his traditional statistics, the popular perception of his candidacy and my JAWS system. Rather than crowding each evaluation with a description of my system, I’ll lay out the nuts and bolts in this space so that readers can refer back to it as needed.

For the uninitiated, JAWS is short for Jaffe Wins Above Replacement Score. Like the famous cinematic shark, the self-referential acronym (introduced within a year after the system’s debut) generally elicits screams at the first hint of its approach. Not everybody can withstand this deep dive into the debate over who is worthy of Cooperstown, but if you’re somebody who likes to chew on the candidacies, JAWS is for you.

JAWS is a tool for measuring a candidate’s Hall of Fame worthiness by comparing him to the players at his position who are already enshrined. It uses the Baseball-Reference version of Wins Above Replacement to estimate a player's total hitting, pitching and defensive value while accounting for the wide variations in scoring levels that have occurred throughout the game's history and from ballpark to ballpark.

A player's JAWS is the average of his career WAR total and that of his peak, which I define as his best seven years (on Baseball-Reference, it’s abbreviated as WAR7). All three are useful for comparative purposes, as Hall of Famers come in different shapes and sizes. Some—such as Hank Greenberg, Ralph Kiner, Sandy Koufax and Jackie Robinson—dominated over periods of time cut short by injuries, military service or the color line. Others—such as Eddie Murray, Don Sutton and Dave Winfield—showed remarkable staying power en route to major milestones. It’s a misconception that every Hall of Famer must do both to be worthy of a bronze plaque in Cooperstown. If you’re using Babe Ruth, Ted Williams or Willie Mays as your yardstick, the institution will become sealed off to virtually everyone.

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For the purposes of comparison, players are classified at the position where they accrued the most value, which may be different from where they played the most games. This happens mostly when players tend to shift to positions that require less defensive responsibility—and thus less overall value—as they age. For example, Ernie Banks played 1,125 games at shortstop from 1953–61 (accumulating 54.7 WAR during that span) and 1,259 games at first base from 1962–71 (accumulating just 12.7 WAR). A small handful of enshrined players with fewer than 10 years of major league service, including pioneers and Negro Leaguers, are excluded from the calculations; 19th century pitcher Al Spalding and former Negro Leagues players Satchel Paige and Monte Irvin, for example, had major league careers too short to use as yardsticks for comparison.

The stated goal of the JAWS system is to improve the institution's standards, or at least to maintain them by identifying and (hopefully) admitting players at least as good as the average Hall of Famer at the position. Setting a lower bar than that not only dilutes the honor but also further strains a system that already has a significant bottleneck. Over the past few years, there have been far more players who measure up than can fit on each voter’s 10-slot ballot (though to be fair, the writers' election of 12 players from 2014–17 matches the largest four-year surge in the institution's history). The idea is to bring a measure of intellectual consistency to an often disorganized debate. Because of that, JAWS has gained a nice bit of exposure in recent years: It's been cited by actual Hall of Fame voters, included within MLB Network'stelevision coverage, and it forms the foundation of The Cooperstown Casebook, my book published by Thomas Dunne Books this past July.

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When I began this series, I used Baseball Prospectus' version of Wins Above Replacement Player, but the 2018 ballot marks my fifth year using Baseball-Reference’s version of WAR. Site owner Sean Forman aided the process by creating several handy tools, including JAWS data on each player page and sortable leaderboards for each position. B-Ref also has other great tools useful to any Hall of Fame discussion, including past voting results, projected future ballots, and the subscription-based Play Index, which allows for custom searches. Want to see the shortstops ranked by fielding runs? The WAR leaderboard since the post-1992 expansion? The Win Probability Added leaders among relievers? It's all a few clicks away.

For all that it includes, it's worth remembering that WAR doesn't capture everything about a player's performance. Recent weeks have seen an interesting debate between leading lights of the sabermetric community—Bill James, Forman, FanGraphs' Dave Cameron, Baseball Prospectus' Jonathan Judge—over the importance of context for a context-neutral statistic. For example, WAR doesn't include anything that pertains to situational hitting. That might be relevant for some purposes—MVP voters might want to know how a player hit with runners in scoring position, or in high-leverage situations—but is ultimately less important over the course of a career, as we generally don't talk about WPA in bulk.

Likewise, JAWS doesn’t incorporate everything that goes into a player’s Hall of Fame case. The system makes no attempt to account for postseason play, awards and other honors, league leads in important categories, career milestones and historical importance; much of that is better handled via the Bill James Hall of Fame Standards and Hall of Fame Monitor metrics, which Baseball-Reference tracks. That information is all germane to the Hall of Fame discussion and can shade an argument for or against a player whose credentials are otherwise borderline, so I’ll incorporate it into my full evaluations.

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My system owes a great deal of inspiration to James's Historical Abstracts, both the 1985 original—which planted the career/peak distinction in my mind—and the 2001 version, which weighted a player's best seasons (using Win Shares) to produce a somewhat more transparent means of combining career and peak into a single ranking. In JAWS, a player's best seasons are effectively double-counted—an appropriate strategy given research into pennants added and the premium value of star talent, in that individual greatness can have a non-linear effect on team results, both in the standings and on the bottom line.

Here are the current positional standards, which have changed slightly following the 2017 elections of catcher Ivan Rodriguez, first baseman Jeff Bagwell and leftfielder Tim Raines:

Position	Number	Career WAR	Peak WAR	JAWS
SP	62	73.9	50.3	62.1
RP	5	40.6	28.2	34.4
C	15	53.4	34.4	43.9
1B	20	66.4	42.7	54.6
2B	20	69.4	44.5	56.9
3B	13	67.5	42.8	55.2
SS	21	66.7	42.8	54.8
LF	20	65.2	41.5	53.3
CF	19	71.2	44.6	57.9
RF	24	73.2	43.0	58.1
CI (1B + 3B)	33	66.4	42.6	54.5
MI (2B + SS)	41	68.0	43.7	55.9
OF (LF, CF, RF)	63	70.1	43.0	56.5
CO (1B, 3B LF, RF)	77	68.0	42.3	55.2
MD (C, 2B, SS, CF)	75	65.9	42.2	54.0
All Hitters	152	67.0	42.2	54.6

As with the past five election cycles I’ve covered for SI.com, I will devote individual articles to the top new and returning candidates, updating my previous work to ensure that it reflects their most recent ballot results and news. I'll also devote shorter writeups to lesser newcomers with no shot at election and batch several of those together. While it's true that I could easily skip the likes of Orlando Hudson and Livan Hernandez, I'm among those who feel that a player's appearance on the ballot itself is worth at least a brief valedictory, and I'm not about to break my Cal Ripken-like streak of covering every candidate.

In my next post, I’ll begin rolling out the top returning candidates. We’ll be onto the new ones soon as well.