Tourneys? That's a tough one as Orks rely more on their opponent not being ready to deal with an Ork army (of whatever build they have) as opposed to having the right tourney units. Orks lack volume of fire in anything Str 8, and cannot get any weapons at Atr 9+ for long ranged support at all. Their best anti-tank in general revolves around charging, yet they are far from the best combat-centric army in the game. They pretty much just come out "slightly above" standard combat, and flat-line there until you get to units like Nobs (which are still far from being 'the best' CC units in the game).
You said you got slaughtered in your first game with Orks. What did you run? If it's a list made of entirely Black Reach kits, I wouldn't honestly be surprised.