Frankly, I think catcher is a dumb name.
One of the fun (at least for me, I know many disagree) aspects of the subclass system is the extra sense of power one can perceive from the title of their role.
You're not just a fighter, you're a bloody Juggernaut for example.
Catcher imo fails this. It doesn't sound like an interesting term.
"These champions primarily rely on ranged fishing tools, setting their team up for success by picking out a vulnerable target for their team to quickly follow up on."
Based on this description, why not call them fishers or reelers?
Or hell, why not call them Warlords? Leaders who pick out targets for their team to capitalize on. I suggest Warlords also because it's the name of a 4e D&D class that was a martial support/leader character who helped his allies through maneuvers and tactical buffs over straight heals.
Alternatively you could scrape the subclass system for a more diverse category system like in Dota 2 (where heroes have multiple things like carry, initiator, etc) but you seem more interested in making subclasses work instead of following Dota (and frankly, I don't think Dota 2 has to worry about what a new character is going to be that often. Which allows for such a diverse classification system).
then?
, the vanguard who isn't a vanguard
, and the tactician who isn't a tactician
!