It's the 2-set bonus. Remember the Gear Planner is only about 1 upgrade at a time.
Replacing your shoulders with the t7.5 ones will activate the 2-set bonus.. in isolation.
Replacing your gloves with the Grotesque ones (without replacing your shoulders) is an upgrade... in isolation.
Ah ok, thank you for clarifying. I thought maybe the set bonus was throwing it off but I figured I'd post here to confirm. Thanks!