I think Nestea was right to say he wasn't in a slump.
He's been in every season of GSL Code S, and I think he's gotten to the Ro16 or better for every one of those seasons. Only Nada has been in Code S for every season since the beginning along with Nestea, but Nestea has had far better performance obviously with his 3 wins. MC, MVP and Zenio have been in Code S for all but 1 season, they are also consistent players.
I don't think you can say someone is in a slump when they're staying in Code S, the toughest tournament in the world. Just because Nestea won 3 GSLs doesn't mean he has to be winning a tournament every other month to be considered not slumping. Nestea doesn't participate in much so he doesn't have that many opportunities to win tournaments. He's had little experience with foreign events and jet lag obviously takes quite the toll on him so I don't consider that slumping. Also, for the foreign events he did go to, he took #2 for Blizzcon, #12 at MLG Providence, and top 16 at MLG Winter Arena. That's not bad for his only foreign performances.