In short, "Strokes Gained" is a value of a golfer's performance compared to the average performance of other golfers.
In 2011, the PGA Tour announced Strokes Gained: Putting.
For example, the average number of putts used to hole out from 7 feet 10 inches is 1.5. If a player one-putts from this distance, he gains 0.5 strokes. If he two-putts, he loses 0.5 strokes. If he three-putts, he loses 1.5 strokes.
In 2014, the PGA Tour announced Strokes Gained: Tee-To-Green. This includes calculations on how to calculate Strokes Gained: Total.
First, a player’s score will be compared to the field’s average to establish a Strokes Gained: Total number. For instance, if a player shoots 68 and the field average is 70, his Total is +2.0. That number, in turn, will equal the combination of Strokes Gained: Putting and Strokes Gained: Tee-to-Green. So if the player is +1.2 in Strokes Gained: Putting, his Strokes Gained: Tee-to-Green number is +0.8.
According to this statement, the equation is: SGtotal = SGputting + SGtee-to-green. However, SGtee-to-green is derived from SGtotal and SGputting values. Thus, a golfer's SGtee-to-green value is inversely proportional to their SGputting value.
Does "Strokes Gained: Tee-to-Green" objectify tee-to-green performance? Is there any correlation between this statistic and the ball striking statistic† + scrambling statistic, its individual parts, or other statistics?
Note: The ball striking statistic and the scrambling statistic doesn't compare to the average performance of other golfers, but does objectively capture driving distance, accuracy, greens in regulation, sand saves, and other around the green recoveries.
† - total driving [driving distance + accuracy] + greens in regulation
For example, Lucas Glover is 1st in Ball Striking, 65th in Scrambling, and 45th in Strokes Gained: Tee-to-Green thus far during the 2016 PGA Tour season.