Of course in very recent performances the picture is a little different
Marsh: .889 OPS in last 7 days
Vierling .818 OPS in last 7 days
Sosa: 1.533 OPS in last 14 days (actually cooled off in the more recent 7)
For Stott you can go much bigger sample: .769 OPS in the second half of the season.
Marsh, Sosa and Stott all carry their weight defensively too. Bohm still trails all of them (and Maton) slightly in WAR (if you include Marsh's AL work). Vierling's just not an everday player I'm afraid.