If you're depending on killing people with Starfall, you'll be greatly disappointed once you reach a few teams that have any clue how to play. Warlock shadowfury, priest/warlock/warrior fear, boomkins typhoon, and ele shammys thunderstorm will interrupt all your guys, and if they are good players, you'll be lucky to get more than a few ticks off. Not to mention if they have a rogue or druid, it's a lot easier for them to find 5 bunched up toons rather than 1.

On my boomkins, I tried opening up with treants + starfall, and a focused hurricane on all, and I would still be very lucky for anybody to drop. I also tried the come out of stealth, and 5x starfire someone. If you think crowd controls are bad on shammys teams, you don't want to see what they look like with that team.

It's definitely a fun team for both world pvp and bgs, but I think if you want any sort of success, you'll have to find a resto shammy. Unfortunately, he'll be the first target every time you start.