Yes, this exactly. One of the PCs' crucial advantages is being underestimated by most opponents. Ten hobgoblins see three humans and think, "Great, we outnumber these guys, let's take them!" and not "We're an Easy encounter for a level 8 party, we're about to become dead."
Right. You can't blame the humanoids for not knowing right away that the pitiful hyoo-man was actually Beowulf or Perseus.
Incidentally, Morlock, I think I just last session named one of my players' warlock patrons after you: Morlock, a pit fiend. I didn't realize until just now that the name was probably on my mind because of you.
The Time Machine, or X-Men comics? Either way, it's one of those cool-sounding names. Better it goes to a Pit Fiend than the goblin who cleans the latrines.

Heh - I've been thinking about this issue over the last week due to one of my Encounters groups deciding that chasing a superior foe was a good idea, even when some of their own party members were bleeding to death on the ground! The foes fled because their leader was down below 10 hp, but then stood and fight when it was apparent there was no other option. The players were very lucky - one PC was conscious when the battle ended and was able to save the other PCs before they bled out!
Again, like the OP, this sounds like one of those good problems. Sounds like the death mechanic in 5e works well. I doubt any of your players missed the mechanical implications of the encounter.
As a player, I always try to have contingency escape plans (especially when I play a wizard!!!). The retreat (or run) adds more interesting tactics to the game.
Indeed. A Noob is a player who hasn't come to grips with his character's mortality. A Vet is a player who has. An Expert is a Vet who has fled and left a party of Noobs to the process of becoming Vets.
