The problem with Sombra is that they have her listed as defense.
She's isn't offense. Sombra isn't offense. Do you fucking understand me? Do you see these words? Sombra isn't a fucking offense character.
Your team gets slaughtered because they are constantly outnumbered because your team has the front liners and a healer and then they have... Sombra.
When you pick Sombra, your team is missing a player because Sombra is always off running around doing whatever the fucking cyber-beaners do.
Sombra is a bad support character. When you pick Sombra, you are actively choosing not to back up your team in any meaningful way. She can't stop the advance like Torb or Sym. She can't heal as well as real healers. She can't kill like a defense or offense. She just runs around los invisible and sorta kinda picks off low health enemies (ay caramba ese). She literally only helps out when she can use her ult and even then it's probably too late to save her poor, outnumbered team.