NCIS: LA - "Vengeance" and this season in general

Okay, what is going on with this show? I started watching it originally sort of intermittently, decided I liked it, and started watching regularly. And for a while it was great! It was your basic cop procedural but I like the characters, and it was all about Sam and G, and their relationship.

It was fun! Sam and G mooned around making eyes at each other; I loved Hetty, and Dom, and Kenzie was okay but not my favorite. And then they started changing things up – got rid of Dom, brought in Deeks, so we lost the chance to watch Sam mentor a young agent and instead got to watch a sleaze leer all over Kenzie. Awesome. (Yeah, yeah, sleaze with a heart of gold, whatever, I don't care.)

(Fair warning, this is long...)

( And then we get to this season. )