Which major professional sport (MLB, NFL, NBA, NHL) has the biggest home field advantage?

A 2011 SBNation article estimated the average extra percentage of games that teams could have won if they played all of their games at home over the preceding three years, and came up with the following stats:

• NBA:  10.11%
• NFL:  6.4%
• MLB:  5.46%
• NHL:  5.22%
• The author was a bit puzzled by that, since playing dimensions don't vary in the NBA (as they do in baseball) and weather isn't a factor (as it is for football and baseball).  
•