From BR Bullpen
James Percy Mason
- Bats Left, Throws Right
- Height 6' 2", Weight 190 lb.
- School University of South Alabama
- High School Murphy High School
- Debut September 26, 1971
- Final Game September 24, 1979
- Born August 14, 1950 in Mobile, AL USA
 Biographical Information
Mason first played with the Geneva Senators in the New York-Penn League in 1968. He was the team's everyday shortstop. In 60 games, his offensive line was .217/.328/.338, leading the team with 33 walks.
Mason was the regular shortstop with the Denver Bears in the American Association the next two seasons. In 1970, he and Jeff Burroughs were the only under-20 players on the team. In 110 games, Mason's line was .241/.333/.377. Defensively, he committed 48 errors, not a good number for a player like Mason who was known for his defence.
During the off-season, the Senators surprised everyone by acquiring pitcher Denny McLain from the Detroit Tigers in return for the left side of their infield, SS Ed Brinkman and 3B Aurelio Rodriguez. The Senators were left with two unproven rookies for the shortstop position, Mason and Toby Harrah, who had played in AA the year before. Harrah, who was the better hitter and was also two years older, got the nod from manager Ted Williams during spring training in 1971 as Mason barely played and was subsequently sent back to Denver. He improved in every aspect of his game in 1971. He led the team with 77 walks, which led to a .389 OBP as the leadoff hitter. He helped Denver win the American Association playoffs over the Indianapolis Indians. He also cut down on his errors with 23 in 102 games at shortstop. In September, he was called up by the Senators, appearing in three games – all starts - and getting his first three hits.
It was back to Denver again to begin the 1972 season. He contributed offensively, with a .272 batting average and a solid OBP of .379. In July, he was called up by the Texas Rangers (the Senators had relocated to the Dallas-Fort Worth area in the meantime) and was immediately installed as the regular shortstop where he remained for the rest of the season. He struggled offensively with a sub-.200 batting average. But he wouldn't see the minors again.
Mason made the major league team out of spring training in 1973 but had to wait until May before getting his first starting assignment He was used often until mid-August and from then on, had only six more starts. He did very well in the first few weeks and was hitting .302 with a .352 OBP in the second week of June. But he hit only .141 the rest of the way. Overall, in 93 games, including 72 starts, his offensive line was .206/.273/.290. For the last two years, the Rangers were juggling about whether to play Toby Harrah at shortstop or third base. Harrah let it be known that shortstop was his preference and with some prospects on the way, the team decided to make him a full-time shortstop for the 1974 season, making Mason available. In December, he was sold to the New York Yankees.
In spring training in 1974, Mason had to compete with Gene Michael for the shortstop job and Mason prevailed. 1974 was the only season where Mason had a regular spot in the line-up for the whole season and he responded with the best numbers of his career. In 152 games, his line was .250/.302/.352.
His next season, 1975, was a nightmare from the offensive standpoint. He was the opening day shortstop but was unable to crack the .200 level the whole season. His best month was August, when he played only six games and had four at-bats! His final batting average was .152 with a .438 OPS. He expected to be traded after the season but in the off-season he joined the Venezuelan team of the Cardenales de Lara in the Winter Leagues. Bobby Cox, who was in the Yankees organization, was their manager and badly needed help in the middle infield. In 29 games, Mason his .352 while playing solid defence. In the playoffs, he hit .327 in 13 games as Lara lost the Venezuelan League finals.
As a reault of his strong winter league performance, he was again the Yankees' starting shortstop on opening day in 1976. In April, he hit .261 and seemed to be on his way to a season like he had in 1974. Then his average was only .136 in May and he had to settle for a final .180 batting average in 93 games. The Yankees made the postseason and after beating the Kansas City Royals in five games, they were swept by the Cincinnati Reds in the World Series. Mason made two appearances against Kansas City and three in the World Series. He had only one at-bat in these five games. Mason made the most of it, hitting a home run in Game 3 of the Series against Pat Zachry. He was the first player to hit a home run in the only World Series plate appearance of his career. There have since been two others: Geoff Blum in 2005, and Bobby Kielty in 2007. He was also the first player to hit a home run in the only postseason plate appearance of his career; Tom Wilson joined him in 2004. Combining these, Mason is the only player whose only postseason plate appearance resulted in a World Series home run. After the 1976 season, the Yankees left him unprotected in the expansion draft and the Toronto Blue Jays picked him up.
Mason was the Jays' main shortstop in their first few weeks of existence in 1977, but in mid-May, he was traded with Steve Hargan and cash to his old team the Texas Rangers for Roy Howell. Mason's days as a regular were over. He was the middle infielder substitute for the next year and a half with the Rangers. Then in December 1978, he was traded to the Montreal Expos for minor league outfielder Mike Hart.
Mason was brought in to add depth in Montreal. The Expos already had veteran Pepe Frias but obviously the team wanted an upgrade over the Dominican. Mason did well offensively in spring training in 1979 and Frias was eventually traded to the Atlanta Braves at the end of the camp. In 1979, the Expos had almost no injuries so the reserves had very few occasions to play. Mason started 16 games, most of them at shortstop as Chris Speier was struggling with a bad back. The highlight of his season was a walk-off RBI double in the 10th inning against the Cincinnati Reds on June 20th. In 40 games, his offensive line was .183/.256/.282. However, he took his back-up role in stride and along with pinch-hitter Tommy Hutton was a leader of the "Bus squad", the Expos' bench that season, "bus" standing supposedly for "broke, underrated superstars". The group also included OF Jerry White, 1B Tony Solaita, 3B Ken Macha and C Duffy Dyer. All of them realized that the Expos were full of talented players who were deservedly starting instead of them and tried to help in whatever way they could the few times they got to play.
However, the Expos wanted more offence from their bench in 1980. In 1979, rookie second baseman Tony Bernazard had showed some promise and the Expos also acquired Bill Almon from the San Diego Padres for Dave Cash. There was no place for Mason and in mid-March, he was released, ending his career.
Because of Mason's low batting average, which hovered just over .200, his name (along with Leo Dixon's) was proposed for inclusion in a new term for poor hitting called the "Mason-Dixon Line" (.204), which is closer to .200 than the Mendoza Line (.215).
 Records Held
- Tied MLB record by hitting four doubles in a game, July 8, 1974
- Brandon Gavett & Lee Ashendorf (May 2003). The Fans Speak Out: Letters to the Editor. Baseball Digest. Retrieved on April 19, 2012.