If someone has to choose between tanking away a match or going for broke and being highly aggressive at every opportunity I'd say that the second option is more mentally useful. Body Language - Freezing up like a rabbit facing a predator to me is the equivalent of tanking. There is a mental lift in being on the attack even if losing is still the outcome. Attacking players have more fun. When you see slumping shoulders that's the first sign. Teach students to stand straight and walk with purpose even between points since your opponent reads body language too. I teach players defense but to always look towards offense especially if you feel mental weakness creeping in. It's better to go down like a Viking.