The Brawlers are the one unit that is present in all NA2 factions (besides the Japanese), despite this they have very different roles within each of those factions due to availability and fireteam differences. Some NA2 armies basically dont use them at all (Foreign Company) while they are backbone troops of others (Druze and Dahshat). Their role within StarCo falls somewhere inbetween as they have a modest AVA but fairly limiting options for fireteams.
By far and away, the most common Brawler you will see on the table with StarCo is the LT. At 16 points and 0 SWC it’s the most affordable LT option in the faction and unless you’ve got an extra 1 SWC laying around for the Aguiciles LT, should pretty much always be your LT choice. The Brigada, your only other choice, might see the table as your LT if you’re running the Brigada/Massacre/Daktari team, but will likely be left at home.
Other than heading up the leadership side of the force, the Brawlers add a couple of other unique elements to StarCo by providing the only access to MSV2, HRLs, and the cheapest AHD in the game. Beyond those, the roles the Brawlers fill are generally better filled with other units available in the force.
What really defines the Brawler’s place in StarCo is the way they are able to form fireteams. They have no Core option and are limited to a Haris (with the possible addition of a CSU and/or Raoul) or a Duo. This mean that even with AVA 4, you will likely never see them as a sizeable focal point of StarCo lists. A Haris with the sniper or HRL is probably going to be the most prominent representation of these mercs on the table. The Doctor and Engineer profiles are only really compelling if used as part of a haris team as the clockmaker/Irmandhinos/Daktari/Avicenna are superior specialists in those roles.
Brawlers are also StarCo’s Spec Ops option, so when using the extra you’ll be bringing a Brawler if you want to take advantage of that. In that instance, utilizing the Spec Ops in a Haris as either an active turn or ARO threat (BS14 Red Fury or BS14 Multi Sniper) gives you some punch that is otherwise lacking in the faction. Used as a solo piece, I would lean towards utilizing it to bolster your defenses with things like minelayer (which is otherwise absent from StarCo) and flamethrowers or go for inferior AD to bring another trooper that can attack from unexpected angles.
All in all, Brawlers fill a very niche role within the faction besides being a common LT option, which means you will be seeing at least one on the table frequently.