I also call more zone plays than I do man and I've had tremendous success in '13. Here's my record so far in my OD to show the kind of success I've had (the top half is total record and the bottom half is the records in USER v. USER games):
I run CPB for the 3-4 as well as all nickle/dime/quarter formations. I run more zone than I do man and when I blitz, I run a lot more zone blitzes than I do man blitzes. By far most of my INTs come from zones (although most of my sacks come from man blitzes).
Against teams that run a lot of curls, cover 2 sink in pretty much any formation is great. Against scrambling QBs, there are quite a few cover 2 sink spy plays.
To stop the outside runs by far my best plays are zones where I've got a couple of flat zones. With those guys (usually CBs) out there in the flats, the runner either runs into him to get tackled or has to turn it back up inside into the meat of my defense. Also, any time a team comes out in an unbalanced formation with all of the WRs on 1 side, I always keep a CB on the empty side (Y + RS ->) so that if they try to run to the emptied side, I have an unblocked CB waiting to make the tackle. Obviously cover 2s are great for having these flats covered, but cover 3s do too. Also, there are tons of zone blitzes that cover the flats and these are some of my best run stopping plays.
Against 3rd and long, and 4 wide my go to is dollar cover 4. This formation covers so much area that it's very difficult to find an open spot. Another great play is the dime 2-3-6 formation (I always
package sub in the DL rush package so it's really another 3-2-6) cover 3 CB man play.
This is a rolled cover 3 with a buzz on 1 side and a flat on the other (but on 3rd and long I always hotroute the flat to another buzz). The thing that makes it unique is that 1 of the CBs (the one on the buzz zone side) plays man against his WR. This can really throw users off as they don't expect to see a combo coverage like that (to my knowledge, this is the only one in the game).
Another of my favorite zones is the 3-4 over ED's cover 3.
This is unique in the game as it's not your typical cover 3 shell with 2 hook zones and 2 flat zones. Instead it's a cover 3 with 2 hooks and 2 buzz zones. For 3rd and medium - long this covers tons of ground. In addition to this, the 2 interior linemen (which is really a DT and a DE) both do stunts which can provide some nice pressure.
The 3-4 has tons of great zone blitzes, all of which can be effective. Here are some (but certainly not all) of my favorites:
These are easily my favorite run defenses:
These are probably my favorite medium range pass zone blitzes:
Some of my favorite nickle/dime zone blitzes: