As a duo, Woods and Watkins produced almost identically per game to their previous years here. The only difference was their roles flipped. And yes, it's fair to look at them as a duo because when they're on the field on any given play only 1 of them can get the ball thrown to them.
Let's look at 2015 (their first year with Tyrod) vs 2017 (their first year with Goff)
2015:
27 Combined Games (13 for Watkins, 14 for Woods)
176 Targets (96 for Watkins, 80 for Woods)
107 Catches (60 for Watkins, 47 for Woods)
1,599 Yards (1,047 for Watkins, 552 for Woods)
12 TDs (9 for Watkins, 3 for Woods)
2017:
27 Combined Games (15 for Watkins, 12 for Woods)
155 Targets (85 for Woods, 70 for Watkins)
95 Catches (56 for Woods, 39 for Watkins)
1,374 Yards (781 for Woods, 593 for Watkins)
13 TDs (8 for Watkins, 5 for Woods)
So was it really that amazing that in the same number of combined games played the duo got 12 fewer catches for 225 fewer yards, but 1 more TD?