Defender medal ?

iScending: If two or more players have reduced equal amount of capture points, the achievement is granted to the player who has earned more XP in the battle (including additional XP provided to Premium account users). If the amount of XP is equal as well, the achievement is not awarded.   I'm afraid the images you provided don't really show if you were eligible  or not but I'm willing to bet someone else from the other team got it due to having higher XP.