A sportsmanlike conduct does in no way veil your skill. Being polite and to acknowledge other people's skill does not make you appear a bad player. Playing in the spirit of sportsmanship does by no means keep you from playing competitively and to strive for victory. The common misconception is that sportsmanship would restrict you. But that's wrong.
Sportsmanship represents no restriction for a good player.
Being skilled and playing effectively and successfully while playing sportsmanlike is no contradiction. In fact I believe that such players are held in higher regards and are more respected than skilled players who display poor behaviour. BTW, sportsmanship does not presuppose skill. But of course it could have an impact on that precious personal score of yours. To disregard sportsmanship and to go deathmatching, or respawn camping, or to join the leading and more skilled team works often wonders on a personal score.