The margins would have been larger if it weren't for some garbage time 3s going down for the opposition. The smaller MOV does indicate that Dallas hasn't played too many complete 48-minute games . When they dominated early, they let the teams back to make the game look closer than it was. Many of the come back wins have been in games where they once led by 10+.
The Sagarin ratings take into account the raw W/L and the MOV but do not give extra weight to recent performances:
http://www.usatoday.com/sports/sagarin/nba0910.htm