LeBron James has averaged 10.2 boards per game in the NBA Finals in his career.

lebron james uncontested rebounds per game in the finals
Interpreted as:
LeBron James uncontested rebounds per game in the last finals
NAMESERIESGPRPGMPGPPGAPGSPGBPGTPGFGMFGAFG%3PM3PA3P%FTMFTAFT%MINPTSREBASTSTLBLKTOVPF+/-
LeBron JamesLeBron JamesNBA Finals5510.242.528.47.81.70.83.910.722.148.41.85.235.25.27.173.12,3371,5625614309346217130-86
StatMuse has game-level data for rebounds per game going back to the 1956 Finals.