I agree with IlliniWarrior on the phrase of over working the soil. It's not the tilling, rather the taking nutrients out of the soil without replacing them. Tilling is necessary to break the hardpan and compaction that occures, though this only has to be done periodically, usually not annually. Good tilth with good levels of necessary nutrients, good moisture and agreeable weather USUALLY yield bounty.. I'm not sure why you tilled it several times, so won't comment.. the end results speak well enough.
It was initially tilled with my monster tiller (since broke), from being grass, when the ground became workable. I purchased a wide body Mantis, and worked it again. Then we were a bit late getting things started and the weeds started growing, so I tilled it again. Then the wife ordered 5 yds of compost, so it got tilled again. But, we ended up with a very productive and fruitful garden. Wife has a crop rotation plan already planned out.
We're like you. Only our season wasn't so productive - but that had to do with all the rain and the overly saturated ground leading to all sorts of fungus problems (a regional issue).
I believe partdeux is referring to comments in other posts about not tilling the soil. And I agree that it would be great to not need to. I have a couple of 4x4 planting boxes with outstanding soil that will never need tilling - but the rest of my garden isn't there yet.
This fall we're not going to let our spent/harvested plants go back to the soil - we're burning them in hopes of getting a handle on the fungus problems. We'll till up everything, spread out the neighbor's manure (yeay, aged cow manure) and spread leaves and grass clippings. Then in the early spring till it all up again. Hopefully a few years of this practice will get us to the soil we want (we have hard clay soil now). And I know that maintaining that soil will be an issue (because each summer the garden will take nutrients from the soil), but I hope that maintenance will require less tilling than we need now.