If you don’t know the basic rules of baseball, I highly recommend that you leave this article immediately. On the other hand, if you (like me) wasted your childhood obsessing over baseball statistics but then got distracted by things like spouses, kids, and football, you’re in the right place. Here’s a relatively brief explanation of the advanced baseball stats you missed along the way, using this excellent book as a guide.
The Basic Idea
The general concept behind the new fancy stats—termed by Bill James as sabermetrics in reference to the extremely geeky Society for American Baseball Research (SABR)—is that the old ones, well, kind of suck.
The point of a baseball game is to score runs and prevent your opponent from doing the same. The problem is that of the three iconic offensive stats—batting average (BA), home runs (HR), and runs batted in (RBIs)—two, namely BA and RBIs, are severely flawed in judging a player’s ability to create runs.
In the case of BA, non-hit methods of getting on base are ignored, and all hits (singles, doubles, triples, and home runs) are treated equally. As a result, the correlation between BA and runs created is not as great as you would expect.
In the case of RBIs, the correlation is obviously better, but far too much depends on external factors. Player A could have the good fortune of frequently batting with runners on base while Player B might not. In other words, Player A’s higher RBI total is partly a measure of the players in front of him.
Similarly, judging pitchers by the unreliable concepts of wins and saves tells us surprisingly little about their ability to prevent runs from scoring. While earned run average (ERA) does have value, we can do even better.
Finally, ranking fielders by errors alone completely ignores things like range (not to mention the subjective nature of what qualifies as an error), thereby telling us little about run prevention.
The bottom line is that the stats you grew up with are bunk. They don’t capture what they claim to capture, and some focus on simply counting numbers rather than providing more useful rates. Even worse, they’re not always adjusted for variations in eras, ballparks, and the like.
The following are the advanced baseball stats you need to understand if you want to grasp what really matters (and get back to spending 486 hours a year watching the sport).
I’ll go through them conceptually, leaving the math aside as I’ve lost confidence ever since I got a D+ on my trigonometry final in 11th grade. If you need to see the math, check out sites like mlb.com, FanGraphs, Baseball Prospectus, Baseball Reference, and Baseball Savant.
And remember, since these types of statistics are proliferating, this is just the tip of the iceberg.
Batting
OBP (On-Base Percentage): As above, BA (Hits dived by At Bats) ignores potential run-producing activity such as drawing a walk, getting hit by a pitch, and hitting a sacrifice fly (none of which are considered at bats!). OBP corrects for this oversight by essentially calculating the number of times a batter reaches base divided by plate appearances (as opposed to the more restrictive at bats). Anything over .370 is great, and over .390 is excellent. Ted Williams is the career leader in this category (.4817), just ahead of Babe Ruth (.4739).
SLG (Slugging Percentage): A straightforward measure calculated as Total Bases Via Hits divided by At Bats. Compared to BA, more weight is given to extra-base hits. Anything over .500 is great, and over .550 is excellent. Babe Ruth holds the highest career SLG at .6897.
OPS (On-Base Plus Slugging): Even though OBP and SLG have different denominators, someone decided we can just add them together to create a new statistic that correlates well with run production (particularly at the team level). Anything over .900 is great, and over 1.000 is excellent. Babe Ruth is the career OPS leader at 1.1636.
wOBA (Weighted On-Base Average): Rather than list a player’s so-called slash line (BA/OBP/SLG—for example, .270/.328/.482), wOBA is a convenient single number that captures the general idea by providing an OBP that is weighted by how a player reaches base (doubles are more valuable than singles and so on). As with OBP, a wOBA of over .370 is great, and over .390 is excellent. And, yes, Babe Ruth is the career leader at .513.
OPS+ (On-Base Plus Slugging Plus): Building on OPS, OPS+ normalizes for factors like ballpark and era. League average is scaled to 100, making 140 (40% better than league average) great and 160 excellent. The highest career OPS+ of 206 belongs to…Babe Ruth.
wRC+ (Weighted Runs Created Plus): Arguably the best offensive metric available, wRC+ builds on wOBA and gets right to the heart of the matter—runs created. Normalized and scaled in the same way as OPS+, a wRC+ of 160 is excellent. You know who is the career leader at 195.
Pitching And Fielding
ERA+ (Adjusted Earned Run Average): This metric takes a familiar calculation (Earned Runs divided by Innings Pitched and then multiplied by 9) and normalizes it for external factors such as ballparks and opponents, allowing for fair comparisons that can even cross different eras. League average is scaled to 100, with 130 being considered great and 160 excellent. The all-time leader in career ERA+ (among those with at least 1,000 innings pitched) is Mariano Rivera at 205.
WHIP (Walks Plus Hits Per Inning Pitched): A simple concept built on the idea that the more baserunners a pitcher allows, the more likely he is to give up runs. A value of 1.10 is great and 1.00 and under is excellent. The career leader in WHIP is Addie Joss (0.9678). Some more familiar names in the top 10 are Mariano Rivera (1.0003) and Pedro Martinez (1.0544).
FIP (Fielding Independent Pitching): A statistic focused solely on events a pitcher has direct control over (strikeouts, walks, hit by pitches, and home runs), thus excluding the luck factor of a good (or bad) defense. The value is multiplied by a constant to put it on a scale somewhat similar to ERA, making 3.50 great and 3.20 excellent. The career leader is Ed Walsh (2.018).
DRS and UZR (Defensive Runs Saved and Ultimate Zone Rating): Two similar advanced baseball stats that attempt to quantify a player’s defensive value, moving us past the flawed error (and associated fielding percentage). The idea is to measure the number of runs a player saves or costs his team in a given season relative to an average player. A value of 0 is average, with +10 being great and +15 excellent. As the data used for these figures is relatively new (2003 onward), it’s hard to compare across eras. It is worth noting, however, that as of 2021, Derek Jeter had the worst career DRS at -165!
The Big Picture
WPA (Win Probability Added): A measurement of how much a player impacts his team’s chances of winning from one event to the next. Over an entire season, each individual event becomes part of a cumulative score, with a full-season value of +3.0 being great and +6.0 being excellent. Barry Bonds is the all-time WPA leader, boasting a career value of 127.66.
WAR (Wins Above Replacement): An all-in-one statistic that takes into account all aspects of the game, adjusting for position and league factors. The result is expressed as the number of wins in a season attributable to a given player relative to a replacement-level player. (The actual number is in runs, and 1 win is awarded for every 10 runs over replacement.) There are a couple different ways of calculating WAR (bWAR and fWAR), but either way, a value between 6 and 8 is superstar material and anything over 8 is insane. Babe Ruth is the all-time leader in single-season bWAR (14.1) and career bWAR (182.4).
Now go apply these advanced baseball stats to the World Series—according to that other esoteric article I wrote last year, a few people are still watching.
