Frontman Dexter Holland explained:
Atom and I wanted to drop you guys a little note, since we know people have been talking about why Atom has left the drummer seat for The Offspring.
The simple truth is that Atom had been working on a few of his own projects during our down time, including Angels & Airwaves but other things too. We think that's great. Unfortunately, in order for him to see those things through he isn't left with enough time to devote to future Offspring stuff. It was a tough choice, but we understand.
Atom's been a great drummer for us and we're sure Pete will be great too!