How come Rudy Gay is not considered as good as Joe Johnson. They have around the same PPG?

Unlike Gay, Joe Johnson knows how to p the ball and is a major threat from the perimeter and beyond the arc. Gay, on the other hand, is a good rebounder but not as effective of a per as Johnson. His perimeter game is decent but not comparable to Johnson's. Their respective teams might also be a reason because the Hawks are a much better team than the Grizzlies.