Since the start of the 2015 season, the San Francsico Giants outfield unit has posted a 10.5 fWAR (Fangraph’s calculation of WAR). That’s good for the second worst outfield unit in baseball since then. For comparison, the Red Sox top the list with a 54.8 collective WAR from their Outfield in the same time-span.
Now, for context, the Padres are in the bottom third of the league in outfield WAR since 2015, and they still have doubled the Giants’ WAR total over that same time period. The league average WAR over that time frame is a 30.