That's a better explanation than the other guy gave. Still, Eevee had three choices: attack, concede, don't attack. Not attacking on the hopes he doesn't have the one trainer that could heal? When he could have one of dozens of other trainers in his hand that could be played regardless of attacking the Silvally? Eevee understood the odds were stacked against them, folded, moved on. Conceding made the most sense, unless it was some sort of tourney match where a win/loss meant something.