Also, I like Taj Gibson on Josh Smith. Historically, Smith has scored over 20 points against Gibson's Bulls once, in 13 games.
http://www.basketball-reference.com/play-index/h2h_finder.cgi?request=1&p1=smithjo03&p2=gibsota01
In three of those meetings, the woeful Gibson has outscored or matched Josh Smith's point totals.
I think those stats show a fairly significant advantage for Josh Smith myself.
15.8 PPG vs 10.1 PPG
8.7 RPG vs 7.2 RPG
3.5 APG vs 1.2 APG
1.4 SPG vs 0.5 SPG
2.1 BPG vs 1.5 BPG
Smith getting to the line 4 times a game vs 1 for Gibson.
Gibson only outscore Smith once, 10 points to 8 on a horrific shooting night from Smith, things he tends to have every once in a while against everyone because he falls in love with the outside shot.
In their playoff matchups the difference becomes even greater in Smiths favor, so say the stats on that page you provided.