I mean, not that it's a 100% foolproof solution, but at some point you gotta step out of what you might consider an ideal composition.
Like, we'll be 2-2-2, but if I'm on support and realise that we just need more DPS and sustain and someone to deal with that damn pharah I'll switch off to soldier. Only 1 support but sometimes you gotta evaluate what your team needs more.
Like yeah, you'll be doing work as reinhardt, but if no one is really utilising what you're used for (i.e. that big rectangle you have) what's the point of a rein? You could be doing better on another character.