Question: Steve Kettmann was a mentor to the minority owner of which MLB team?

Context paragraphs:
List of New York Yankees managers: The New York Yankees are a professional baseball team based in New York City, New York in the borough of The Bronx.  The New York Yankees are members of the American League (AL) East Division in Major League Baseball (MLB).  The Yankees have won the World Series 27 times, more than any other MLB team.  In baseball, the head coach of a team is called the manager, or more formally, the field manager.  The duties of the team manager include team strategy and leadership on and off the field.  Since starting to play as the Baltimore Orioles (no relationship to the current Baltimore Orioles team) in 1901, the team has employed 34 managers.  The current Yankee manager is Joe Girardi, the current general manager is Brian Cashman and the current owners are Hal and Hank Steinbrenner, who are sons of George Steinbrenner, who first bought the Yankees in 1973.

John I. Taylor: John Irving Taylor (January 14, 1875 – January 26, 1938) owned the Boston Red Sox from 1904 until 1911.  He was the son of General Charles H. Taylor, publisher of the Boston Globe.  He purchased the team from Henry Killilea on April 19, 1904, with his father Charles serving as a minority owner.  In September 1911, the Taylors sold half of the stock in the team to Jimmy McAleer and Robert B. McRoy with McAleer taking over as team president.  On December 21, 1913, Joseph Lannin, Frank P. Cooper, and John R. Turner purchased McAleer and McRoy's half of the team with Lannin becoming team president.  On May 15, 1914, Lannin bought out all of his partners and became sole owner of the Red Sox.

Posting system: The posting system (ポスティングシステム , posutingu shisutemu ) is a baseball player transfer system that operates between Japan's Nippon Professional Baseball (NPB) and the United States' Major League Baseball (MLB), or between the Korea Baseball Organization (KBO) and MLB.  Despite the drafting of the United States – Japanese Player Contract Agreement, unveiled in 1967 to regulate NPB players moving to MLB, problems began to arise in the late 1990s.  Some NPB teams lost star players without compensation, an issue highlighted when NPB stars Hideo Nomo and Alfonso Soriano left to play in MLB after using loopholes to void their existing contracts.  A further problem was that NPB players had very little negotiating power if their teams decided to deal them to MLB, as when pitcher Hideki Irabu was traded to an MLB team for which he had no desire to play.  In 1998, the Agreement was rewritten to address both problems; the result was dubbed the "posting system".

Steve Kettmann: Kettmann, despite having written on a wide variety of topics, is best known for his work on several baseball books, most recently "Baseball Maverick: How Sandy Alderson Revolutionized Baseball and Revived the Mets" (Grove Atlantic, April 2015).  The book explores Alderson's role as general manager of the Oakland A's in the 1980s and 1990s, including his role as a mentor to the young Billy Beane, who was later made famous in the movie adaption of the Michael Lewis book "Moneyball".  It also focuses on Alderson's years as general manager of the New York Mets starting in late 2010.

Billy Beane: William Lamar Beane III (born March 29, 1962) is a former American professional baseball player and current front office executive.  He is the Executive Vice President of Baseball Operations and minority owner of the Oakland Athletics of Major League Baseball (MLB).  Prior to his front office career, he played in MLB as an outfielder between 1984 and 1989 for the New York Mets, Minnesota Twins, Detroit Tigers, and Oakland Athletics.  He joined the Athletics front office as a scout in 1990.  He was named general manager after the 1997 season, and promoted to executive vice president after the 2015 season.

1967–68 Houston Mavericks season: The 1967–68 Houston Mavericks season was the first season of the Mavericks in the American Basketball Association.  On February 2, 1967, Houston was awarded a franchise for $30,000 with William Whitmore, Charles Frazier and Cloyce Box being the buyers.  Later that year, T.S. Morrow and Bud Adams, owner of a Houston-based oil company and the AFL's Houston Oilers bought Box's interest in the team.  Morrow would be majority owner while Adams was a minority owner.  The team had less than steller attendance, with 3,091 attending the first ever game versus the Chaparrals on October 23, 1967 (losing 100–83).  The lowest attended game was held on February 5, 1968, when only 575 people attended.  The highest attended game was on February 29, 1968, with 4,965 attendance.  Despite all of this, the Mavericks spiraled into the playoffs, in part due to 8 of the 11 teams in the new league being guaranteed a spot into the Playoffs, with Houston getting the final spot by 4 games.  In the Semifinals, they were swept by the Dallas Chaparrals in 3 games.  This was their only playoff appearance in their two-year history.

Cap Anson: Adrian Constantine Anson (April 17, 1852 – April 14, 1922), nicknamed "Cap" (for "Captain") and "Pop", was a Major League Baseball (MLB) first baseman.  Including his time in the National Association (NA), he played a record 27 consecutive seasons.  Anson was regarded as one of the greatest players of his era and one of the first superstars of the game.  Anson spent most of his career with the Chicago Cubs franchise (then known as the "White Stockings" and later the "Colts"), serving as the club's manager, first baseman and, later in his tenure, minority owner.  He led the team to five National League pennants in the 1880s.  Anson was one of baseball's first great hitters, and probably the first to tally over 3,000 career hits.

Super Bases Loaded 3: Super Bases Loaded 3 (known in Japan as Super Moero!!  Pro Yakyuu) is a Super Nintendo Entertainment System baseball game.  It is the seventh overall installment of the "Bases Loaded" series, and the third installment of the secondary series for the Super NES.  "Super Bases Loaded 3" was licensed by the Major League Baseball Players Association (MLBPA) and uses real MLB players, but it was not licensed by Major League Baseball (MLB).  All 28 U.S. cities that had an MLB team at the time are listed but team names and logos are not given.  No real stadiums are used and the World Series is renamed the championship tournament.

Brandon McCarthy: Brandon Patrick McCarthy (born July 7, 1983) is an American professional baseball pitcher for the Los Angeles Dodgers of Major League Baseball (MLB).  He has also pitched in MLB for the Chicago White Sox, Texas Rangers, Oakland Athletics, Arizona Diamondbacks, and New York Yankees.  In addition, he is a minority owner of the Phoenix Rising FC, a United Soccer League team.

Jeffrey Vinik: Jeffrey N. Vinik (born March 22, 1959) is the current owner of the Tampa Bay Lightning (NHL) and the Tampa Bay Storm (AFL), as well as a minority owner of the Boston Red Sox (MLB).  He served on the board of directors for Liverpool Football Club of the Premier League from 2010-2013.

Supporting paragraphs: Steve Kettmann Billy Beane
Answer: Oakland Athletics