James "Firebat" Kostesich is definitely one of the most popular members of the Hearthstone community. Aside from being a loved streamer and content creator in general, he's actually had quite a lot of success as a professional player as well, with his winnings totaling at over $200,000 since he started way back in 2014.
He's obviously able to pilot any kind of deck, but he's been quoted saying that he enjoys bringing Priest decks to tournaments as a way to give himself a challenge and make it more entertaining for the viewer. It's things like this that earned his adoration from the community.
Most recently he had been playing for Cloud9, but yesterday on Twitter he announced that he would be parting ways with the organization.
I enjoyed my time on team @Cloud9, but I am going in a different direction than competitive play, so we are parting ways.— James Kostesich (@firebat) March 16, 2017
The key takeaway from this tweet is where he mentions pursuing a "different direction than competitive play."
This could mean a lot of things.
Perhaps he's following Lifecoach's example and retiring out of frustration with the state of the current competitive environment, or perhaps he's merely going to become a full time streamer? As you become more popular in esports, more money can be made streaming than competing.
He was also seen as a commentator recently for the PAX East Major, so it's also quite possible that he's also seeking further opportunities as a caster. Whatever he decides to do, I'm sure he'll find success!