I would have to say it takes a different amount/variety of skill.

As a boxer, we blow people up, but that's because it is frequently 5 vs 1.
Even in arena, when it is two players against five players, we have synchronous attacks.
Which is a massive advantage over even 5 different players.
But it is also a massive disadvantage in the number of different actions we can do at once.

Our skill is more with setting up macros and keybinds to coordinate the team, even when people are playing as individuals against us.
We have a lot of firepower and resiliency compared to a single boxer, but five players can do five things at once, we have to coordinate our team with one set of hands.
In general, a large portion of the player base does battlegrounds as a means to get gear; and a lot of players both our allies and our enemies are undergeared -- we run BG's for gear too.

It is easier to kill 1 person as a 5-box team, then to kill 1 person as a 1-box solo player.
But in a battleground its not 1 vs 5 all the time, but sometimes it is.
In AV, 5 players in one place and moving as a group is a drop in the bucket.
In WSG, 5 players in one place is half of the team, and potentially a disadvantage.