Just had a lovely game where on defence, we had three healers and the last person who picked Ana, despite seeing we had a mercy and zen already, refused to switch. What is it with people in this game sometimes? Of course we lost the 1st point on Anubis in 60 secs.
I've said it before. But Zen is barely a healer. I feel like he's closer to a range DPS with his utility being support. His ult is great, but you need to absolutely have a Mercy or Ana to make up for his weak single target healing.
If the Zen is good at range and focuses on DPS. You basically have someone with Soldier's range, but hits harder.
So I don't actually think it's a terrible comp. It's definitely not a bad one and I would say even err on the side of good. It will have strong healer and good range. Weakness would be if they ran a slightly tankier team with Genji or Mercy.