This is what I'm assuming.
Zane's dad was lonely, so he made some other robots to go and find him. The Ninja, naturally, assumed they were a new threat and started fighting them. Then the summer heat wave came, and the ninja decided to only wear part of their masks.
Ninjago has gone a far way from its quaint origins in 2011. That was were it actually made a bit of sense and had a place in time. That was when they were actually Ninja. Then Sensei Wu revealed that his father invented the wheel and the internal combustion engine and things got messed up. At least the Ninja don't do drugs yet.
70722 OverBorg attack
Lloyd has now fulfilled his destiny in the toy market. Now the LEGO company has no qualms about putting him in a cheap set. The Overlord has injected his essence into a random guy off the street, who asked Zane's dad to replace his eye and give him a climbing vehicle with extra arms, which in turn has another vehicle with giant saw arms. Which apparently are also wheels.
Well, we get some regular forest green pieces for the first time since Mata Nui knows when. And more Exo-Force arms. And even more slopes. You can never have enough slopes.
And a green trash can. Meet Lloyd, Ninja of Rubbish.
70721 Kai Fighter
This set is named after the single minifigure with a bazooka, not the red jet that makes up 90% of the set. Seriously, LEGO, learn how to spell, and capitalize correctly. There's no way you're avoiding potential religious quarrels by putting "Chi" in all caps.
We get some new armor, which is nice. We also get Kai's hair for the first time. *cue applause*. Speaking of which, the General Cryptor figure has a more Ninja-like torso and legs than Kai does.
Also, I didn't forget, Kai carries the new collectible of 2014 -- the elemental saw blades. What's Sensei's excuse for their existence now?
Oh, about the plane. It's red and gold. It doesn't have a lot of slopes. It has angle plates, and that fin from the 7774 Crab Crusher, and two unshapely blocks on either side. Oh, and that Great Devourer venom has now infected the support elements. But, as I said earlier, you can never have too much forest green.
70723 Thunder Raider
Cole has stolen Kai's mech and turned it black. How I wish for the Exo-Force sets were Click Ball Joints were plentiful. Wait, do I see dark brown Ball-joints?
Jay has a tank, which I assume is the title vehicle. Tank treads, more cheese slopes, and oh? What's this? A handle to push the tank with! And missiles which apparently don't fire, but the flick-fire missiles of the past five years never fired anyway.
There's another "Nindroid" (call me crazy but I can still have my doubts) that has a Gatling gun. It has beams of suspended illuminated neon particles which provide a link to the muzzles. (In other words, there's transparent stuff holding up non-transparent stuff.) This also has another magic saw blade.