Why Bob Gibson’s 1968 season will never happen again
In 2019, I stumbled upon a video by Jon Bois called “The Bob Emergency”, an account of the greatest athletes in professional sports who went by the name Bob. The video looked at the storied history of athletic Bobs dating back to the 1850s to the Present while highlighting their peak and steep decline. Jon Bois has a way of making videos that no one can replicate, but he also has a way of uncovering stories that are not told very often. At the end of part one of his series, he tells the story of Bob Gibson, a pitcher for the St. Louis Cardinals from the 60s who was an above-average pitcher in the early to mid-60s. But in 1968, Bob Gibson bested one of the greatest seasons in baseball history.
In 1968, Bob Gibson in 304.2 innings pitched bested an ERA of 1.12, a major league live-ball era record that has not been broken by a qualified starting pitcher since Gibson set it in 68'. Some consider it to be the best season of all time because of this, but it takes a full conceptualization of Bob Gibson’s 1968 season to understand how special it was.
There is not a lot of metrics that are good at measuring a pitcher’s performance in the 1960s. While ERA has always existed, it is not the best metric in determining a player’s performance because it does not factor into account a park factor nor the team’s defense. However, the metrics that can best evaluate players in the live-ball era, pre-flyball data, are Fielding Independent Pitching (FIP), ERA- and Fangraphs Wins Above Replacement(fWAR). Other metrics can be used, but I am going to stick to these for now.
FIP takes into account only what the pitcher can control, Strikeouts, Home Runs, and Walks. While K/9, BB/9, and HR/9 are all good metrics, FIP takes all of them into account rather than 3 separate metrics. FIP- is just FIP compared to the average FIP that particular season, plus it takes into account the park factor. This is important because it adjusts to the league average, which will be important later.
ERA is earned run average, which just looks at how much a pitcher gives up in a given game. ERA- is just like FIP- just with ERA, taking into account the season and park factor.
fWAR is a measurement by Fangraphs in looking at the value of a player in wins above any average player. This metric is FIP-based, with extra calculations from Fangraphs to give more weight to their metric. I will be using this WAR metric to encompass the best 500 seasons since 1920 because it focuses on the metrics above.
I will be looking at players in what is called the live-ball era, a period after the reforms by MLB that regulated unfair pitching practices like the spitball among other things. This era is from the 1920s to the present and is best to be evaluating pitchers when they were put at a disadvantage.
For an outline of this article…
I will be going into 1968 Bob Gibson’s historical ERA in terms of its scale to the rest of the league in terms of value and volume, while also highlighting how his ERA meets the ERA- scale throughout history.
I will be also going into Bob Gibson’s FIP over innings pitched, innings pitched per game, and FIP- to see how it scales to the rest of history.
I will be giving more insight into what the 304.2 Innings Pitched means in 1968 and 2021, by looking into historical trends in regards to Innings Pitched and Innings Pitched per game.
And finally, I will put 68' Gibson’s WAR calculations in context and explain where he fits among the greatest live-ball-era pitchers.
68' Gibson’s ERA in Context
When it comes to a pitcher compared to his relative field, no one in the number of innings pitched did it like Bob Gibson. Here is the 1.12 ERA in reference to the Top 500 fWAR seasons since 1920 over innings pitched.
In neon green is Gibson. No one comes close. Even when pitching half the amount of innings Gibson pitched, no one touches Gibson’s historic mark.
When looking at the ERA- scale, which is a scale that takes into consideration park factor and the league average ERA at the given year on a scale of 100 (110 is below average, 90 is above average), Gibson posted a 38 ERA-. To put that into perspective, in the live-ball era, that is 5th most of all time, and 3rd most when discounting the 60 game season in 2020 by Trevor Bauer and Shane Beiber.
1968 Bob Gibson is the green dot while the rest of the field are the top 250 fWAR seasons since 1920. 2000 Pedro Martinez is at the bottom with a 35 ERA- followed by 1994 Greg Maddux with a 37 ERA-. Right after Gibson is followed closely by 1995 Maddux with 39 ERA- and 1999 Pedro with 42 ERA-. But what makes Gibson’s 1968 season truly impossible to achieve ever again is the number of innings pitched while dominating every time. Maddux and Pedro, while having dominant seasons in their respective years, pitched less than 90 innings than Gibson in 1968, and those who pitched more or similar to Gibson in regards to the volume are not even close to his splits.
The reason that Maddux and Martinez are highest despite having lower ERA’s in their respective seasons is that 1968 was a pitcher-dominated season, having 3 of the top 20 ERA pitchers in the live-ball era, and an insanely low average ERA compared to today. ERA- factors in league average, which would in theory make Gibson’s ERA numbers less impressive when adjusting it for today’s era. Yet it still holds up as the 5th most ERA- in the live-ball era and 3rd most among qualified pitchers in the live-ball era.
68' Gibson’s FIP in Context
The graph below is among the 500 best fWAR seasons after the live-ball era. The minimum fWAR requirement to meet the Top 500 is a 5.5 fWAR.
On the x-axis are total innings pitched in that given season and on the y-axis is the season’s FIP total.
Keep in mind, when looking at this graph, and the other graphs that measure player performance over innings pitched in regards to the ones above, it only evaluates seasons within the Top 500 fWAR single seasons, which has a minimum of a 5.5 fWAR. This means all of these pitchers are legit studs.
When you look at the bottom of the graph, you can see 1999 Pedro Martinez. In my opinion, I don’t think any season (even 68’ Gibson) compares to the insane numbers he put up in that year, with a 1.39 FIP, 37.5% Strikeout percentage, 0.38 HR/9, and a 42 ERA-, in 213 innings pitched.
You can see 2021 Corbin Burnes in the bottom left-hand corner. His 1.63 FIP is a historic low among qualified pitchers and among pitchers who have a high fWAR, but he has pitched the least amount of innings among this field.
Both of these trends are also similar if we look at the time and FIP over Innings Pitched Per Game (IP/G)
What made Bob Gibson so special was the fact that he completed almost all the innings he pitched in. At the very end of the chart in regards to Innings Pitched per game is 1969 Bob Gibson and 1968 Bob Gibson. While 1969 Bob Gibson was a historic season in its own right, 68' Bob Gibson is one of the biggest outliers in any of these graphs.
Pedro is at the bottom in regards to FIP, with Burnes, Gooden, Kershaw, Seaver, Koufax, etc., all with a sub 2 FIP. But no pitcher with a sub 2 FIP has more IP/G than 68' Bob Gibson, which puts Gibson in a league of his own as a high volume, high production pitcher, among the greatest of all time. Seeing Bob Gibson in the bottom right corner of this graph means he is both durable and excellent with no middle ground.
Now Gibson’s FIP- is not as impressive on an all-time scale as the other metrics above.
Gibson’s FIP- is at a very good 65, but not as impressive as his 38 ERA- in the same season. Looking at the graph, he is below the trend line in FIP at his amount of innings pitched, but he still is not an outlier in this graph. In fact, in the 1968 season, he was 2nd in FIP-. This 65 FIP- is because FIP- and ERA- measure among the league average in a given season which in 1968 was historically unprecedented. In 1968, the average ERA was a 3.47 and FIP constant of 2.3, truly insane metrics. Again, for reference, in 2016 the FIP constant was 3.1 and the league average ERA was 4.16. From this, there is an argument to be made that this diminishes Gibson’s 1968 season because all pitchers in 1968 were pitching exceptionally well, but I would say this builds on Gibson’s resume. The fact that Gibson was able to set himself apart from not only the dominant 1968 class, but the entire history of Major League Baseball is something to take into account. But even with the low FIP- relative to the history of the league, volume still needs to be taken into account when looking at Gibson and the 1968 season. Here is Gibson’s ERA and FIP over innings pitched among the 76 qualified pitchers in the 1968 Season.
As before, Gibson’s ERA more than separates itself from the pack (highlighted in neon green), with a higher volume than most of the pitchers in general and the highest ERA in history as said before. Gibson’s FIP also leads the league for that year (highlighted in pink). Luis Tiant follows closely at a 1.6 ERA and just above a 2 FIP, an astounding season all time, and having a 7.4 fWAR, putting him in the Top 100 best seasons in fWAR in the live-ball era. However, Tiant still pitched about 50 innings less Gibson, while Gibson still had a better FIP and ERA than Tiant. This can also be seen in IP/G in the 1968 season.
Gibson on this graph produces the most in regards to volume per game while having the lowest numbers on the chart. And while Tiant is not far behind when it comes to the difference between their FIPs, he pitched about an inning and a half less a game with 19 complete games compared to Gibson’s 28. Even in a volume-driven era with 300 inning pitchers being normality, Gibson still lies as an outlier.
So while yes, his adjusted FIP is not as impressive as his other stats, in context with the amount of volume he took on in that season compared to other pitchers is no easy task.
68' Gibson’s Volume in Context
This graph is the trend in innings pitched for the Top 500 fWAR seasons in the live-ball era. The reasoning for this is to see how many innings an ace pitched for their team in a given season (A 5.5 fWAR is in the top 3% of all players in 2010 and only 4 pitchers in 2021 and 3 pitchers in 1968 met the 5.5 fWAR thresholds).
We can see a very steep slope downward trend towards fewer innings pitched in a given year among the best pitchers in the league. This makes sense for a multitude of reasons, player safety, the team’s increased usage of bullpens, and other factors that have made 300 innings pitched season unheard of. In 2021, 4 pitchers pitched over 200 innings (two don’t meet the fWAR threshold). Among the Top 500 fWAR seasons, only 18 of them were less than 200 innings, almost all of them in the 2000s besides Koufax in 1962 which was shortened by injury.
The neon green dot is 1968 Bob Gibson, with an astounding 304.2 innings pitched. Although many pitchers in the live-ball era had thrown more than him in a given season, he was well above average for his era. But no one with that amount of volume touched him in regards to his quality of pitching. In the FIP over innings Pitched graph, you can see that only 1963 and 1965 Koufax reached a sub 2 FIP with over 300 innings pitched in a season.
We can see a similar trend in regards to Innings Pitched Per Game (IP/G). The list of pitchers in this sample is the same but only taking out any pitchers that are not designated as relief pitchers
This chart seems off and looks like the pre-Bob Gibson era was a weird one in regards to Innings Pitched Per Game. And that’s because among the starting pitchers, many of them produced a massive amount of innings, but many were given relief duty or early relief duty in regards to the division of games over innings pitched creating these massive outliers in the 20s through early 60s.
The metric above divides the number of games a starting pitcher started by the number of games a starting pitcher appeared in, in the regular season. For example, even though Lefty Grove is considered as a starting pitcher, he still only starts about half of the games he pitches in, which puts him at the bottom of the graph. And the straight line of pitchers from the 60s onwards would see the starting pitcher stay in his role almost 100% of the time across 60 years. One of these years, was 1968 Bob Gibson, who never pitched a reliever inning in 68' or 69', most likely because no relief pitcher even came in for Gibson in 28 out of the 34 games in 68'. Gibson should be considered as the biggest workhorse of all time in regards to IP/G, posting a staggering 8.94 IP/G. Looking at the chart, no one in the live-ball era comes close to Bob Gibson except…
Woah, look at that it’s 1969 Bob Gibson! (Who is the black dot in the graph) Well and 1924 Dazzy Vance.
Just like the trend of innings pitched over time drastically decreasing as player health is being taken into account, the amount a pitcher throws in a given game also had to drop to preserve arms. Looking at Corbin Burnes’s Cy Young 2021, he pitched just under 6 innings per start, about 3 fewer innings a game than Gibson.
68' Gibson’s WAR in context
Finally, let’s look at WAR.
WAR stands for Wins above replacement, as said before, and can be calculated in many different ways. Fangraphs WAR is something that uses Fielding Independent Pitching (FIP) as a basis for their calculation, to take into account what the pitcher can control. Then there is RAR, Baseball-Reference WAR, and RA9 WAR, WAR that takes into account Fielding Dependent Pitching (FDP) along with FIP. RA9 WAR specifically looks at how many runs a pitcher gives up per 9 innings and calculates FDP wins by metrics such as Ball In Play wins and Left on Base wins to look at things FIP doesn’t take into account. Any WAR calculation in a given season is culminating, so it takes into account volume in the calculation, and the higher the WAR the better.
When looking at RA9-WAR over fWAR, this is what shows.
As you can see, 68' Gibson lies well above average in fWAR, standing out from the cluster in the Top 500 to Top 100. Gibson’s 1970 and 1969 season has a higher fWAR than his 1968 season. However, Gibson lies above the whole graph in RA9-WAR at 13.5 and in the 93rd Percentile of the Top 500 pitchers in fWAR at 8.6. This gives a clearer picture of how his volume ended up creating more of an impact for a team in terms of wins and also rewards high volume and high production seasons unlike other metrics without context. While his season among a FIP base was not as impressive as his ERA numbers, his RA9-WAR allows for more context on how some of his numbers are truly the greatest in the live-ball era.
What does all of this mean?
In any season, the more a pitcher pitches, the bigger chance that a player gives up a big hit or loses their command of the zone. We see this in seasons that can be derailed by injury, rule changes, baseball consistency, and other factors that worsen as sample size increases. It is much easier to have a 1.00 ERA for example with 100 innings pitched rather than a 1.00 ERA with 200 innings pitched. This is especially the case in IP/G, which is why teams usually take out their starting pitchers right after the 5th or 6th inning. This isn’t a bad thing at all, and by no means am I saying that these pitchers should be penalized on an all-time scale due to the actions of their clubhouse. However, it would be a disservice to the greatness of 68' Bob Gibson to not recognize his record-breaking ERA and his insanely good FIP is on top of the fact that he was one of the most used pitchers in a given game ever.
Now, I am not saying this is the best season of all time. I think it’s close, but 1999 Pedro Martinez is one of the most insane seasons of all time, and his numbers could be as good if not better if given the extra 100 innings to pitch. But 68' Bob Gibson is a season that will never happen again. The amount of volume that Bob Gibson had taken on in the course of the 68' season, as well as the 1969 season, was truly insane. Bob Gibson made the best pitchers in baseball history look painfully average. But the thing is, all those seasons shown above are outliers in their own right. According to Fangraphs, there were about 7,493 pitchers since 1920 that have been designated as qualified. The top 500 fWAR seasons that all are marked above a 5.5 are about the top 6% of pitchers in the past 101 years. So when seeing Bob Gibson’s point on a graph be as much as an outlier as he was, with the amount of volume he took on is truly impossible to ever see a season like his ever again.
Resources:
Here are some explanations of metrics from Fangraphs.
FIP: https://library.fangraphs.com/pitching/fip/
FDP and RA9-WAR: https://library.fangraphs.com/pitching/fdp/
ERA- and FIP-: https://library.fangraphs.com/pitching/era-fip-xfip/
fWAR: https://library.fangraphs.com/war/differences-fwar-rwar/