Just wondering if it's possible to win by building a top notch offense with limited defense in a zone set?

On some level..........but the problem is that if your defensive ratings are too weak, many of your guys will foul out a lot, hence limiting your offense. 

I've won a national championship with a D3 squad that had averages of 50/50 ath/spd, and close to 50/50 LP/PER with an average defensive rating in the mid 30's. That's not to say I didn't have one or two players with 70+ defense, but overall I had a team that was just so high-powered on offense that they could outscore practically anyone.

But also, I ran a press and had a very deep team, with even my 11th or 12th man able to put up 10-15 points if my starters fouled out. My general conclusion so far is that you need some defense, and at least one very talented defender, but you can win it all with a high-powered offensive team. If anything, it provides a bit more of a challenge than simply trying to build a team on ATH/DEF. It's also more fun personally to see my teams score 100+ points a game and to see different players putting up gaudy numbers every night. 

I think you can.  My team is built a lot like this.  I still need to take another step in order to win a title, but I am getting closer.  

www.whatifsports.com/hd/TeamProfile/Ratings.aspx

Alright thanks! so it is possible to be effective