Home Park Effects on Performance in the American League 
By Pete Palmer If a player bangs out 26 doubles, 27 homers, scores 84 runs and drives in 117, it is considered a pretty good season. Well, these are the figures that Lou Gehrig achieved in 1930, IN 78 ROAD GAMES! Probably the single most startling fact unearthed by a comprehensive study of player and team performance at home and away in the American League is that Yankee Stadium, certainly known to be difficult for righthanded batters, was not that easy for lefties either. In general, though, the home park can have a significant effect on both batting and pitching statistics. First let us evaluate the average advantage for the home team. Normally, the host club wins about 54 percent of the games, although the edge has diminished gradually over the years. From 1901 to 1920 it was 55.3%, from 1921 to 1940  54.7%, from 1941 to 1960  54.3% and from 1961 to 1977  53.6%. There is a difference of about ten percent in the rate runs are scored home and away. But since the home team bats in about five percent fewer innings than the visitors, the total surplus is cut in half. Batting average, onbase average and slugging percentage are about five percent higher for home team players, as run scoring is proportional to the product of onbase average times slugging percentage. This product, called batter run average, is therefore up about ten percent. For pitchers, earned run average is down about ten percent and winning percentage about 80 points higher. Of course, certain parks deviate from this norm considerably, several by as much as ten to 15 percent. In addition, some parks favor right or lefthanded batters, with the result a variation in the 2540 percent range. The purpose of this study is to take into account the home park effect when evaluating batters and pitchers. These effects are not easily noticed, even by an interested observer. A player who hits 50 points better at home in the course of a season will add only about one extra hit per week. One season is really not enough to evaluate the home park effects, because the normal variation in play is large compared to the differences expected. If data on a number of players over several years show a park to be much easier to hit in than normal, certainly this should be considered when evaluating players on that team. Can a club tailor its players to take advantage of the home park structure? Since Tom Yawkey rebuilt Fenway Park in 1934, Boston has played .594 at home and .459 away, a difference of .135. The league over this period was only .540 at home (.460 away) or plus .080. Thus the Red Sox have won about four more games each season than average during these years. On the other hand, the Yankees have won only 51 more games than average at home in 55 years while playing in the stadium, a little under one win per year. Now let's look at all the parks. In order to rate each one of them, the total number of runs scored and allowed at home and away was found for every club. The park rating is simply the average number of runs scored by both teams at home divided by the average number of runs scored by both teams on the road.
*new layout for park that underwent major changes The Red Sox and Angels make an interesting comparison. Starting in 1969, Boston has average 331 runs scored per year away from home, and 319 runs allowed. The league figures are 324 scored and 334 allowed. The Sox pitching is second best to Baltimore considering runs allowed away from home. On the other hand, California has averaged 304 scored and 347 allowed. Their pitching ranks tenth on the road. The importance of .the home park can be clearly shown using Babe Ruth as an example. The Babe received some raves in 1918 for hitting 11 homers. All were away from home. John Tattersall determined that this tied the alltime record for road homers. And Ruth did this in only 47 games with a ball that was so dead that the league homers per game were the lowest in history. Converted to a regular in 1919, Babe banged out 29 homers. This time he put 20 out of bounds in opposing lots. Fenway Park was so difficult for homers that only four were hit there all year, not counting the Babe. Now, when Ruth went to the Yanks, a simple calculation could be made to show that he had a good chance at 50 homers, even without the juicedup ball. Homers at the Polo Grounds were about four times more frequent than in Boston in those days. Ruth hit 9 at home in 1919 in 63 games, 4 at New York in 11 games and 16 at all the other parks in 56 games. Switching him to New York and adjusting the games in each park for the full 154 scheduled, one gets a predicted total of 28 in the Polo Grounds, 2 at Fenway and 19 in the other parks, or 49 in all. Actually he had 29, 5 and 20 for 54. In fact, in 1920 Ruth had the single most impressive season at home of any player in history. His batting mark was a mere .397, but his slugging percentage was an incredible .985 (201 total bases in 204 atbats). His batter run average was almost four times the league average. No one else has come close in this department, except for Ruth again in 1921 and 1923 when he was around the 3.5 mark. In 1921, Babe slugged .929 at the Polo Grounds, second highest alltime. He had a tough year in 1922, when he was suspended for barnstorming, and by 1923 the Yanks were in their new stadium. The tables show that no lefty, including Ruth, has benefited greatly by playing in Yankee Stadium. Ruth's 5% advantage is a bit below the 10% norm. Lou Gehrig, who did not pull the ball as much as Ruth, actually was hurt considerably by his home park. Assuming the average increase if he were a home team player, Gehrig probably would have done better at any other field except Washington, where he batted only .319. In contrast, he hit .381 at Comiskey Park in Chicago, and .380 in Detroit. He set the following season road records: most doubles, 36 in 1927; most RBIs, 117 in 1930; most total bases, 247 in 1927 and 1930; highest slugging average, .805 in 1927; most long hits, 69 in 1927; most extra bases on long hits, 125 in 1927; and most times on base, 186 in 1931. Joe DiMaggio also had difficulty in New York, but primarily because he was a righthanded batter. He hit .315 there while batting .334 at Boston. However, his batting at Fenway Park was no better than his overall road figures. The argument that if the Yankees had traded DiMaggio to the Red Sox for Ted Williams, both players would have had even more spectacular careers, does not appear to be valid. Williams hit .361 at Fenway, while batting only .296 in New York. This comes as no surprise after reviewing the data on Ruth and Gehrig at Yankee Stadium. Of course, you have to keep in mind that Ted was going against the Yankee pitching staff, which was about ten percent better than the league average while he was playing. And before you jump to the conclusion that DiMag was a better road hitter than Williams, remember that Joe had the advantage of counting Fenway in with his road parks, while Ted was stuck with the stadium. Here are some of the home and away figures for selected Yankees and Red Sox.
The data for Fenway Park show that a typical increase in batting average at home for most righthanders and some lefthanders is 50 points. The normal 5% improvement would be about 15 points. Since half the games are played at home, this would result in an overall rise in lifetime batting average of one half of 50 minus 15 or 17 points, quite a lot. There were two other parks that produced significant increases in batting, but both were for lefthanders. League Park in Cleveland, which was remodeled in 1910 and was shared with Municipal Stadium by the Indians from 1932 to 1946, had a high right field wall that was 290 feet away at the foul line and 340 to the rightcenter power alley. To left the distances were 375 and 415. Tris Speaker hit 306 doubles there in 11 years, only 179 on the road. Sportsman's Park in St. Louis was slightly larger, 3 10 down the line in right and 354 to rightcenter, but only 351 and 379 to left, and was therefore a better park overall for hitters. Detroit, which favors lefthanders slightly today, was quite different in Ty Cobb's era. The right field wall was moved in almost 50 feet in 1938.
Looking at the other parks, we find that Griffith Stadium in Washington and Municipal Stadium in Cleveland, before the fences were moved closer in 1970, were particularly difficult for hitters. Most of the new stadiums, such as Baltimore, California and Oakland, have helped lower the overall hitting statistics of the league. Comiskey Park, now White Sox Park, in Chicago has had a number of alterations over the years, but has remained slightly below average for hitters. But the original Chicago park was quite different. South Side Park helped to inaccurately coin the "Hitless Wonders" tag for the 1906 outfit. Chicago was actually second in the league in runs scored on the road, while their pitchers were just a bit better than average, but at home they allowed only 180 runs in 79 games, by far the lowest in history. The 1909 Senators set an alltime futility record with 197 runs scored at home and 183 on the road, while the Athletics that season set a record with 208 runs allowed away from home. The 1950 Red Sox tallied the most runs at home, 625, while the Yanks of 1930 made 591 on the road. The 1939 Browns allowed 561 in St. Louis, while the A's one year later allowed 523 in away games. For individuals, Ted Williams had the best single season road record, based on BRA divided by the league average. Ted hit 26 of his 38 homers away in 1957 and is the only player to have a rating better than three times that of the league. Ruth's 1920 slugging comes second, so that was easily the best overall season, home and away. Harry Heilmann set the standard for road batting with 134 hits and an average of .456 in 1925. Lou Gehrig had 247 total bases in 1930 along with his 117 RBI, and we have already mentioned his great 1927 season on the road. Ruth had 87 walks in 1920, 32 homers in 1927, and 87 runs in 1928. Williams had a .528 onbase average and a .417 BRA, 3.34 times the league average, in 1957. The road mark for triples is 15, set by Ty Cobb in 1908 and tied by Dale Mitchell in 1949. Ruth holds most of the home records, 1920  .985 slugging, .531 BRA, 3.96 normalized BRA, 1921  94 runs, 63 long hits, 134 extra bases and 1923  194 times on base. Joe Jackson batted a cool .488 at home in 1912, Sam Crawford hit 18 triples in 1914, George Sisler had 150 hits in 1920 enroute to a .473 batting mark, and Tris Speaker batted out 42 doubles in 1921. Hal Trosky had 251 total bases in 1936, while 1938 saw Hank Greenberg smash 39 homers and Jimmie Foxx drive in 104 runs. Counting road games only, Lou Boudreau was the last of the .400 hitters, with a .403 mark in 1948. The data on pitchers shows quite a variation from park to park. On the average, the ratio of earned runs per game at home over that on the road should be about ten percent lower than the park rating. Differences from this can generally be attributed to actually pitching better or worse at home. Ed Walsh and Doc White make a good example of this. Since their park had an 88 rating, their ERA ratio should be 90 percent of that, or about 80, while their wonlost percentage should be up about 80 points at home. However, Walsh won nearly as many games on the road as at home and his ratio was higher than expected, 86 percent. White, on the other hand, pitched much better at home, as shown by a greater than 200 point gain in percentage, and his ratio was down to 68. Vida Blue, Jim Hunter, Nolan Ryan and Frank Tanana are all quite a bit more effective at home than might be expected by their low rating. In fact they all have ERA's about onehalf a run per game lower overall because of pitching in large parks. Ed Walsh had a 23 and 5 mark in 1908 at home, with 11 shutouts. In 1904, Jack Chesbro won 20 at home, and completed all 25 starts. He also won 21 on the road, against 5 losses, and pitched 23 complete games. Addie Joss had an 0.81 ERA on the road in 1904, also 0.99 at home in 1908, but Hub Leonard holds the home record with 0.84 in 1914. Walter Johnson had a neat 204 road record in 1913, and came within one win of beating each rival at least twice at home and twice away. He split two decisions against Boston in Washington. Lefty Grove was unbeatable at home. From 1929 through 1933 he was 751, including a 171 mark inl93l. Lefty also won 19 straight at home from 1938 to 1941. Whitey Ford had identical .690 percentages home and away. Fenway Park has been particularly difficult for opposing pitchers. In order to make a fair comparison, the pitcher's ERA at Fenway Park was related to the average number of earned runs per game scored there by the Red Sox during each pitcher's career. Jim Bunning and Hal Newhouser were the most successful of the visiting hurlers, and Ted Lyons did fairly well, but a number of good pitchers were quite ineffective at Fenway. Whitey Ford's fine overall road record was helped by the fact that his appearances there were limited.
Player lifetime performance was evaluated counting home 1/8, road 7/8 and allowing for strength of own teammates, as a batter does not have to face his own pitchers and vice versa. National League seasons were included for the twoleague players. Performance during 194345 was devalued by 15 percent. For batters, league average data was increased by 5 percent so that pitcher hitting totals would not inflate the result. The rating is player BRA over league BRA for best seasons up to 600 road games. For pitchers, batting was rated 1/10 and pitching 9/10. The rating is league ERA over pitcher ERA for best seasons up to 1000 road innings. A 150 rating is worth about four extra wins per season for 150 games batted or 250 innings pitched.
