The added advantage is your opponents regular premier league 11 this season is basically players that would been Carabao cup players in the past (seriously, go check their typical starting players now, its dire). So can you imagine what the reserves to their starting 11 mediocre youngsters and overall washed players, who will play against you this game, will be like? They will be all academy players most likely. Zero quality depth.
While your reserves playing this will likelybe likes of Giroud/Batushayi, Pedro, Hudson Odoi/Pulisic, Barkley etc, all players Man U wished they could for their first eleven this season