It's not just one thing with the Kraken. IT's like every single thing of him has had NO testing.
His flying is a huge advantage. A lot of hunter weapons (Lightning gun, for example) are close range so his flying makes them much harder to use. Trapping him is a must to do absolutely anything to him.
Vortex deals a ton of damage AND pushes you halfway across the map. It can completely stop a chase, or blow half your team out of position, letting him wrap up.
Lightning does insane damage AND it's harder to dodge then the rock throw AND he's SO much safer casting it since he's going to be in the air and everyone is so busy dodging they can't shoot him.
Hey, it's a Beta (Alpha, whatever) and I'm sure they're going to tweak him, but as of now, he's completely OP. Goliath feels like he's in a MUCH better place (I win matches and loses matches with him. Even at level 3 a good hunter team can take him down, and even when he's level 1 he can escape and do a few good hits.)
At this point, if you're playing Kraken, you're the guy who picked Akuma in Turbo. He's just a broken character, IMO.