Lol. Here's something general I'll bring up. With brawl's floaty mechanics, teching people often serves no purpose, because the floatiness isn't keeping them to the ground, unlike on Melee.
Thus, many people can sit back, camp, and spam without much worry of overdoing their spam attacks, because the game is simply slower. Thus, people CAN play highly defensively and out-patience their opponent.
However, if you play to get better, you're not going to win by playing as exclusively conservative as you do. Camping and spamming is probably the best strategy ( except for techy improvisation) in Brawl, but you need to get your blood flowing and really play fast and sort of intense.
Marth is a character who can beat most players without playing fast, because of his move speed, range, and power, but good players are good because they understand the metagames of certain characters. Campers/ spammers are difficult to defeat, regardless of their play speed, but the best players will beat them because they're aware of how dumb their play outside of that strategy is.
In Melee, predictability wasn't too big of an issue because you could naturally combo people because of the strong gravitational pull. Now, it's huge, because you can now avoid any combo, forcing the aggressor to having to improvise and make opponents make mistakes--mindgames.
Unfortunately, I think the DK you were playing wasn't very smart, and that's why you got so many attacks in as you did. If you were playing mine or all the other many good DK's, they would have spot dodged your fsmashes, grabbed you, and comboed you to utter hell.
Develop your "hit and run" game. And when I say that I don't mean hit and then run away to the edge, I mean attacking, dodging a short distance away from opponent, and doing that again quickly. Of course, if you do have a combo opportunity take advantage of it.
Attacking and then fleeding to the edge is just stupid. You can't control the play as much as the circumstances I'm describing if you do anything mindless, HOWEVER effective it might seem. When you stay near your opponent and pressure their shield and general welfare, you are necessarily in control.