Honestly, it feels like if we don't have a Mercy on our team, it's an auto-loss if the enemy do. Which is why I'm stuck playing her - and fucking hate competitive because of it.
The whole overwatch is a mess and will be until rez gets removed completely. Its very stupid mechanic and not competitive at all when a team tries and kills a target you just bring him back with a button and nothing else and the disadvantage becomes even again.