Expansion, the Strike Zone and the Year of the Pitcher: Baseball from 1961 to 1968
How baseball grew from 16 teams to 20, why a wider strike zone helped pitchers take over, and how 1968 became the Year of the Pitcher, with league-wide scoring figures from the historical record.
Between 1961 and 1968 the major leagues changed shape and then changed their minds. The sport grew from 16 clubs to 20, Roger Maris hit 61 home runs, a new generation of pitchers learned that the strike zone had become much bigger, and by 1968 the average team scored 3.42 runs per game, the lowest figure in the historical record since 1908. In the National League, Bob Gibson finished with an earned run average of 1.12. In the American League, only one hitter in the batting-title race finished above .300.
That collapse in offense produced the label the Year of the Pitcher, and it also produced a response. The rule makers lowered the mound and shrank the strike zone for 1969, and they split each league into divisions at the same time. This article explains how the eight years fit together: the expansion that diluted talent, the rule that changed the zone, the pitchers who used it and the 1968 season that forced baseball to act. Every league figure comes from the historical record through the 2025 season.
From 16 clubs to 20
For most of the twentieth century the major leagues were stable at eight clubs in each league. In 1961 that changed. The American League added two clubs: the Los Angeles Angels and a new version of the Washington Senators, after the old Senators moved to Minnesota and became the Twins. In 1962 the National League followed with the Houston Colt .45s and the New York Mets, which brought National League baseball back to New York after the Giants and Dodgers had left for California in 1958.
The effect on the sport was large. In 1960 there were 16 teams, and by 1962 there were 20. The historical record shows total attendance of 18,894,518 in 1961, with 18 clubs, and 23,102,745 in 1968, with 20. Each new club needed a full roster, and the players came from a pool that had supported 16 teams a year earlier. The standard argument is that expansion dilutes talent, giving hitters and pitchers more weak opponents to face, though in practice the pool was growing as well, including from the integration of the 1950s and the recruitment of Latin American players. Read the integration era for the earlier part of that story.
The new clubs were as bad as everyone expected. In 1961 the Angels won 70 and lost 91, and the new Senators went 61-100. The 1962 Colt .45s went 64-96, and the Mets, managed by Casey Stengel and playing at the Polo Grounds, went 40-120, a record that became part of baseball's folklore. Seven years later the same Mets won 100 games and finished first in 1969, the year the league expanded again. The 1960s are an era where it is easy to find examples of both despair and resurgence.
1961: the 61 home runs and the 162-game schedule
The first expansion season is remembered for a hitting duel. Roger Maris of the Yankees hit 61 home runs in 1961, and his teammate Mickey Mantle hit 54, according to the historical league leaders. Orlando Cepeda of the Giants led the National League with 46 home runs and tied Maris for the major-league lead in runs batted in with 142. Maris was named the American League's Most Valuable Player and Frank Robinson the National League's.
What made the number a controversy was the schedule. The American League had expanded to 10 teams and a 162-game season, whereas the National League still played 154 games in 1961. Babe Ruth's record of 60 home runs, set in 1927, came in a 154-game season, and the commissioner at the time, Ford Frick, ruled that a player who passed Ruth after the 154th game would have his total listed separately from the original record. Maris hit his 61st on the final day of the regular season. The story of an asterisk in the record book is a popular one, but no official asterisk was ever used; the rule was a ruling about how to describe the achievement.
The Yankees won 109 games and beat the Cincinnati Reds 4-1 in the World Series. Whitey Ford won 25 games and the Cy Young Award, which in those years went to one pitcher for both leagues, and Sandy Koufax of the Dodgers led the majors in strikeouts with 269. Offense was healthy: league-wide, 1961 teams averaged 4.53 runs and 0.95 home runs per game, the highest figures in the stretch this article covers.
The year the zone grew
For 1963 the rule makers rewrote the strike zone. Before the change, the zone was defined as the area over the plate between the hitter's armpits and the top of his knees. From 1963 it ran from the top of the shoulders to the bottom of the knees, and so it was taller at both ends. A pitcher who could throw to the top and bottom of that area had a much larger target, and an umpire who called it as written took away a hitter's best pitches to drive.
The league-wide results are in the table below, which the historical team records can produce for every year.
| Year | Teams | Runs per team-game | Home runs per team-game | Strikeouts per team-game | League batting average | League ERA |
|---|---|---|---|---|---|---|
| 1961 | 18 | 4.53 | 0.95 | 5.23 | .258 | 4.03 |
| 1962 | 20 | 4.46 | 0.93 | 5.42 | .258 | 3.95 |
| 1963 | 20 | 3.95 | 0.84 | 5.80 | .246 | 3.46 |
| 1964 | 20 | 4.04 | 0.85 | 5.91 | .250 | 3.58 |
| 1965 | 20 | 3.99 | 0.83 | 5.94 | .246 | 3.50 |
| 1966 | 20 | 3.99 | 0.85 | 5.82 | .249 | 3.52 |
| 1967 | 20 | 3.77 | 0.71 | 5.99 | .242 | 3.30 |
| 1968 | 20 | 3.42 | 0.61 | 5.89 | .237 | 2.98 |
| 1969 | 24 | 4.07 | 0.80 | 5.77 | .248 | 3.61 |
The step from 1962 to 1963 is the clearest sign of the rule's effect: runs per team-game fell from 4.46 to 3.95, the batting average fell from .258 to .246 and the strikeout rate climbed from 5.42 to 5.80. Nothing else changed that year in a way that explains the drop. After 1963 the numbers hover around four runs per game for several years, then slide further in 1967 and 1968. Between 1961 and 1968 the average team's scoring fell by about a quarter and its home runs by more than a third.
The strikeout column deserves attention. It rose from 5.23 to 5.99 between 1961 and 1967, and then eased to 5.89 in 1968. This means that the 1968 collapse in runs was not entirely about strikeouts; the batting average fell to .237 and the home runs fell to 0.61 per game, so hitters were making less contact and less damage on the balls they put in play.
The Dodger pitchers and the ballparks
The pitchers who used the zone best were in Los Angeles. Sandy Koufax went 25-5 with a 1.88 earned run average and 306 strikeouts in 1963, 26-8 with a 2.04 earned run average and 382 strikeouts in 1965, and 27-9 with a 1.73 earned run average and 317 strikeouts in 1966. He won the Cy Young Award in each of those three seasons and the pitching Triple Crown in each as well, and the historical record lists them as his three Cy Young Awards, the Most Valuable Player award in 1963 and two World Series MVP awards. Koufax retired after the 1966 season, at the age of 30.
His teammate Don Drysdale pitched alongside him, and in 1968 Drysdale went 14-12 with a 2.15 earned run average, a year in which he also put together a streak of scoreless innings that stood as the major-league record for two decades. Between them, and the park they pitched in, the Dodgers built an identity around run prevention. Dodger Stadium opened in 1962, and many observers of the time considered it a pitcher's park, though the historical record cannot separate the effect of a ballpark from the quality of the pitchers.
Another park-related change came in 1965, when the Astros moved into the Astrodome, which the historical record shows list as their home through 1999. That ballpark is the subject of its own article on domed stadiums, and it began a trend in which the setting of the game was no longer a given.
1968: the Year of the Pitcher
The numbers in 1968 are unusual even in this run. The average team scored 3.42 runs per game. The American League as a whole hit .230, the National League .243, and the major leagues .237. The league earned run average was 2.98.
The individual numbers were more extreme. In the National League, Bob Gibson of the St. Louis Cardinals went 22-9 with a 1.12 earned run average in 304 2/3 innings and struck out 268, which is the lowest earned run average for a qualifying starter since 1914. In the American League, the earned run average leader was Luis Tiant of Cleveland at 1.60, with Sam McDowell second at 1.81 and Wilbur Wood third at 1.87. Denny McLain of the Detroit Tigers went 31-6 with a 1.96 earned run average and 280 strikeouts in 336 innings, and he won both the Cy Young Award and the Most Valuable Player Award in the American League. Gibson won the same pair in the National League.
McLain's 31 wins have not been matched since: no pitcher has won more than 27 games in a season since 1968, in the historical data through 2025. At the other end of the spectrum, Carl Yastrzemski of the Boston Red Sox won the American League batting title with a .301 average, and the next two hitters were Danny Cater at .290 and Tony Oliva at .289. The best hitter in the league barely cleared .300. In the National League, Pete Rose led at .335, and Frank Howard of the Washington Senators led the majors with 44 home runs, a total that would not have impressed anyone a decade earlier.
The postseason ended with a seven-game World Series. The Cardinals, who won the National League pennant with 97 wins, faced the Tigers, who won the American League with 103. Detroit won the series 4-3, after trailing three games to one. Gibson struck out 17 batters in Game 1, which remains a World Series record, and Detroit's Mickey Lolich won three games, so the series was decided by pitchers as well.
Why scoring fell: the candidates
Nobody can say how much of the 1968 drop came from each cause, and the useful way to think about it is as a set of contributing factors.
- The larger zone. The 1963 rule is the best-documented cause, and the 1963 drop in the table supports it.
- The mound. The rules allowed a mound of up to 15 inches, and in several parks groundskeepers favoured the home pitcher. A higher mound makes the pitch come downward at a steeper angle. The historical record has no data on mound heights, so this is a mechanism, not a measurement.
- Strikeouts and style. Hitters swung for power and struck out more, and pitchers learned to throw sliders and fastballs up and down in the zone. The strikeout rate rose by more than 14 percent between 1961 and 1967.
- Parks and conditions. New ballparks, including Dodger Stadium, the Astrodome and Shea Stadium, were built with large dimensions or a pitcher-friendly design, and the move to night games continued.
- Talent. Expansion thinned the pool of hitters, but it also thinned the pool of pitchers, so the net effect is unclear.
A responsible conclusion is that the zone was the largest single change that can be tied to a date, and the rest were working in the same direction. The slide from 1963 to 1968 was gradual enough that no single season's rule can explain it.
The response: 1969
After 1968 the rule makers acted. For 1969 they lowered the maximum mound height from 15 inches to 10 and shrank the strike zone back to the area from the armpits to the top of the knees. They also expanded to 24 teams, with Kansas City, Seattle, Montreal and San Diego joining, and split each league into two divisions, which created the league championship series. The mechanics are the subject of the 1969 reforms.
The table shows the result. Runs per team-game climbed from 3.42 in 1968 to 4.07 in 1969 and 4.34 in 1970, and the league batting average rose from .237 to .248. It is hard to find an example of a rule change that changed results as quickly. The new teams, though, were poor: the Montreal Expos and San Diego Padres each lost 110 games in 1969, the same year the Mets won 100.
The era was followed by the free-agency fights of the 1970s, which are covered in the free agency era. For a fan of statistics, the lesson of 1968 is that a number only has meaning inside its own year.
Reading statistics across the 1960s
The most practical use of this history is as a warning about comparing players across eras. A 3.00 earned run average in 1968 was an ordinary number, because the league average was 2.98, whereas the same figure in 1961, when the league average was 4.03, would have been excellent. Statistics such as ERA+ and OPS+ exist to make that comparison automatic, by expressing a player's result relative to the league's.
A few rules of thumb help:
- Compare a player with his league and year first, then with other eras.
- Treat league batting average, runs per game and earned run average as part of any story about a player.
- Be careful when ranking leaders from 1963 to 1968 against those from the late 1960s, when the zone and the mound changed.
- Remember that expansion in 1961, 1962 and 1969 changed the number of players and opponents.
The same lessons apply to the development of hitters in any decade: what a hitter can do depends on what the rules and the environment allow him to do.
Common questions
Why is 1968 called the Year of the Pitcher? Because league-wide scoring hit its lowest level in the live-ball years, with 3.42 runs per team-game, a league batting average of .237 and a combined earned run average of 2.98, and because Gibson and McLain posted extraordinary seasons.
Did the strike zone change cause the low scoring? It is the best-documented cause. The 1963 zone widened the target, and the league's runs per game dropped from 4.46 to 3.95 that year, but several other factors also played a part.
How many teams were there in 1968? Twenty, ten in each league, with no divisions. The 1969 season added four more teams and divided the leagues.
Was there an asterisk on Roger Maris's 61 home runs? Not officially. The commissioner's ruling distinguished a 154-game record from a 162-game one, but no asterisk was used in the record books.
Did the changes of 1969 work? They did, in the sense that scoring recovered at once: 4.07 runs per team-game in 1969 compared with 3.42 in 1968.
Where to go next
For the rules that followed 1968, read the 1969 reforms, then see how those playoffs work today in the guide to the MLB postseason. For a view of the sport after the strike zone and the mound had been reset, look at the free agency era. You can compare the pitchers of any era with the current ones on the career leaders pages, and the stats and analytics topic page collects explainers for the adjusted measures mentioned above.