I'm confident 10 well prepared goblins could defeat a lv10 ranger on their turf (a dense forest or cave) with preparation. Hit and run tactics are very powerful. With traps, poison, bait and time-triggered distractions he will eventually exhaust his spell slots and healing. Vietcong tactics. Like what Brutus used at the dragon. If they have tunnels to pop up everywhere, shoot and retreat he has no chance.
Well, that's my interpretation. I wouldn't know and I don't have the time to learn how to dm.