Question: Who was the head coach during the 1999 season in which Ben Wallace was traded from the Washington Wizards?
Context: The 1999–2000 NBA season was the 11th season for the Orlando Magic in the National Basketball Association.  During the offseason, the Magic hired Doc Rivers as Head Coach while acquiring Tariq Abdul-Wahad from the Sacramento Kings, Chris Gatling from the Milwaukee Bucks, Ben Wallace from the Washington Wizards, second-year forward Pat Garrity from the Phoenix Suns, and rookie Corey Maggette from the Seattle SuperSonics, while signing free agents John Amaechi and Monty Williams.  The Magic's transition continued at midseason, trading Abdul-Wahad and Gatling to the Denver Nuggets for Ron Mercer, Chauncey Billups and Johnny Taylor.  However, Billups never played for the Magic due to a shoulder injury he sustained in Denver. The 1999–2000 NBA season was the Wizards' 39th season in the National Basketball Association.  During the offseason, the Wizards acquired Isaac Austin from the Orlando Magic, and signed free agents Aaron Williams and Michael Smith.  The Wizards continued to under achieve with a 14–30 start as head coach Gar Heard was fired and replaced with Darrell Walker.  Despite posting a solid 10–7 record in March, the Wizards finished last place in the Atlantic Division with a 29–53 record.  Top draft pick Richard Hamilton averaged 9.0 points per game off the Wizards bench.  However, the biggest news would involve the front office as retired Chicago Bulls star Michael Jordan joined the team as Vice President.  Following the season, Austin was traded to the Vancouver Grizzlies, Tracy Murray signed as a free agent with the Denver Nuggets, and Williams signed with the New Jersey Nets. The 2016–17 Washington Wizards season was the 56th season of the franchise in the National Basketball Association (NBA) and 44th in the Washington, D.C. area.  On April 14, 2016, the Wizards fired Randy Wittman after the team missed the playoffs.  On April 26, 2016, the Wizards hired Scott Brooks to be their head coach.  The Wizards clinched a playoff berth on their 129–108 victory over the Brooklyn Nets on Friday March 24, 2017 after having a one season absence from the playoffs.  On March 28, 2017, the Wizards defeated the Los Angeles Lakers 119–108 to win their first division title since 1979 ending their 38 year drought when they were named the Bullets. The 2003–04 NBA season was the 63rd season for the Pistons, the 56th in the National Basketball Association, and the 47th in the Detroit area.  Despite a solid year last season, the Pistons received the second overall pick in the 2003 NBA draft, which they obtained from the Memphis Grizzlies.  They selected Darko Miličić as their top pick, but only used him as a reserve as he played limited minutes off the bench.  After their first trip to the Conference Finals since 1991, the Pistons hired Larry Brown as head coach.  Under Brown, the Pistons were once again a tough defensive team as they went on a 13-game winning streak between December and January.  However, after a solid 33–16 start, they struggled in February losing six straight games.  At midseason, the team acquired All-Star forward Rasheed Wallace from the Atlanta Hawks after playing just one game for them.  With the addition of Wallace, the Pistons won 16 of their final 19 games finishing second in the Central Division with a 54–28 record.  Ben Wallace was selected for the 2004 NBA All-Star Game. The 2011-12 Washington Wizards season was the 51st season of the franchise in the National Basketball Association (NBA), and the 39th in the Washington, D.C. area.  The Wizards finished the lockout-shortened season with a 20–46 record and in 14th place in the Eastern Conference.  It was the last season of Flip Saunders as Washington's head coach, who was fired after 17 games.  For the 2011–12, the Wizards unveiled a new logo and color scheme, bringing back the "hands" logo used during the 90s when they were still called the Washington Bullets. The 2003–04 NBA season was the Wizards 43rd season in the National Basketball Association, and their 31st season in the city of Washington, D.C..  With All-Star guard Michael Jordan retired for good and Doug Collins fired as head coach, the Wizards hired Eddie Jordan, and signed free agent and last year's Most Improved Player Gilbert Arenas during the offseason.  Under Jordan, the Wizards showed signs early into the season as they won their first game against the Chicago Bulls 99–74, and held the Toronto Raptors to 60 points in a 26-point margin win, while winning three of their first five games.  However, with team captain Jerry Stackhouse playing just 26 games due to knee injuries, the Wizards played mediocre basketball all season finishing sixth in the Atlantic Division with a disappointing 25–57 record, missing the playoffs for the seventh straight season.  Following the season, Stackhouse was traded to the Dallas Mavericks, and Christian Laettner signed as a free agent with the Miami Heat. The 1998–99 NBA season was the Wizards' 38th season in the National Basketball Association.  Prior to the start of the season, which was delayed by a four-month lockout, the Wizards acquired All-Star guard Mitch Richmond and Otis Thorpe from the Sacramento Kings.  Richmond had a solid season leading the team in scoring averaging 19.7 points per game.  Meanwhile, Rod Strickland finished second in the league with 9.9 assists per game.  However, the Wizards continued to under achieve as head coach Bernie Bickerstaff was fired after a 13–19 start, and was replaced with Jim Brovelli midway through the season.  The team lost seven of their final nine games finishing sixth in the Atlantic Division with a disappointing 18–32 record.  Following the season, Thorpe signed as a free agent with the Miami Heat, Calbert Cheaney signed with the Boston Celtics, Ben Wallace was traded to the Orlando Magic, and Brovelli was fired as coach. Ben Camey Wallace (born September 10, 1974) is an American retired professional basketball player.  A native of Alabama, Wallace attended Cuyahoga Community College and Virginia Union University and signed with the Washington Bullets (later Wizards) as an undrafted free agent in 1996.  In his NBA career, Wallace played with the Washington Bullets/Wizards, Orlando Magic, Detroit Pistons, Chicago Bulls and Cleveland Cavaliers. James Leonard Hamilton (born August 4, 1948) is an American basketball coach and the current men's basketball head coach at Florida State University.  He is a former head coach at Oklahoma State University, the University of Miami, and for the National Basketball Association's Washington Wizards.  In his 23 years as a collegiate head coach, his teams have qualified for seven NCAA tournaments and eight NITs, highlighted by appearances in the NCAA Tournament's "Sweet Sixteen" in 2000 (with Miami) and 2011 (with Florida State).  While with the NBA's Wizards his team posted a 19–63 record during his sole season with the franchise in 2000–01. The 2000–01 NBA season was the Clippers' 31st season in the National Basketball Association, and their 17th season in Los Angeles.  During the offseason, the Clippers acquired second-year guard Corey Maggette from the Orlando Magic, and Sean Rooks from the Dallas Mavericks.  With the addition of Maggette along with rookies Darius Miles, Quentin Richardson and Keyon Dooling, who was also acquired from the Magic, the Clippers were a young team.  However, center Keith Closs was suspended for the entire season due to lack of physical conditioning.  Under new head coach Alvin Gentry, the Clippers would struggle losing 7 of their first eleven games as Tyrone Nesby was traded to the Washington Wizards.  However, they would play around .500 in the final three months of the season, as they doubled their previous season's win total finishing sixth in the Pacific Division with a 31–51 record.  Second-year star Lamar Odom had a strong second season leading the team in scoring and rebounding.
Answer: Doc Rivers