I mean, there's a decent bit of RNG to it.
On my lower ranked account that I'm climbing on sometimes I'll get matches where we have 5 support mains and me. But we're "favored" to win that match
Against a team that has a rein/orisa, d.va, mercy, zen, solider, junkrat mains.
Sometimes you gotta take your L
But your winrate should still be positive.