context: In 1981, after the 1980–81 season, Johnson signed a 25-year, $25-million contract with the Lakers, which was the highest-paying contract in sports history up to that point. Early in the 1981–82 NBA season, Johnson had a heated dispute with Westhead, who Johnson said made the Lakers "slow" and "predictable". After Johnson demanded to be traded, Lakers owner Jerry Buss fired Westhead and replaced him with Riley. Although Johnson denied responsibility for Westheads firing, he was booed across the league, even by Laker fans. However, Buss was also unhappy with the Lakers offense and had intended on firing Westhead days before the Westhead–Johnson altercation, but assistant GM Jerry West and GM Bill Sharman had convinced Buss to delay his decision. Despite his off-court troubles, Johnson averaged 18.6 points, 9.6 rebounds, 9.5 assists, and a league-high 2.7 steals per game, and was voted a member of the All-NBA Second Team. He also joined Wilt Chamberlain and Oscar Robertson as the only NBA players to tally at least 700 points, 700 rebounds, and 700 assists in the same season. The Lakers advanced through the 1982 NBA Playoffs and faced 1981–82 Philadelphia 76ers season for the second time in three years in the 1982 NBA Finals. After a triple-double from Johnson in Game 6, the Lakers defeated the Sixers 4–2, as Johnson won his second NBA Finals MVP award. During the championship series against the Sixers, Johnson averaged 16.2 points on .533 shooting, 10.8 rebounds, 8.0 assists, and 2.5 steals per game. Johnson later said that his third season was when the Lakers first became a great team, and he credited their success to Riley.
question: How many more rebounds did Johnson average than assists during his championship series against the Sixers?
answer: 2.8