Kaku had a dip in production in the second half of last year where he started off leading MLS in assists and then had no assists at all for quite a long time. He then didn't make Paraguay NT, which meant a lot to him to the point he changed his citizenship from Argentina. The bottom line is, your belief that he struggled because he wanted to leave is a pure speculation, given that he really wanted to make Paraguay NT and already had some struggles last year, so this was not a new phenomena to go through below average spells, and he is back to playing well again. Murillo as you said didn't have an offer that we know of and sucked, while Lawrence did and did't go, yet produced well. So, all in all, there does not seem to be an evidence to suggest plays start to suck when we get a bad offer for them and decide not to move them.
As far as Kaku's friends, I think if the club treated Kaku well otherwise, and we offer his friend good money, he would not be opposed to come here. Think about this, we spent entire last summer negotiating for Kaku, working with agents, and got him for $7 mil transfer fee, plus some other expenses to agents, etc... Then he has a very good season, makes Paraguay NT (I think he actually started there when Liga MX called), and as you just said, was MLS MVP caliber player. And we only got 1 full year out of him. So, is it unreasonable to ask 12 mil transfer fee to start negotiations with Liga MX? I don't think so.
I don't think what RBNY asked for was unreasonable at all and I mostly agreed with their decision not to sell, given the offer. My point was, that there is a risk in doing what RBNY did and that's having an unhappy player, which Kaku clearly was for a large part to season and it showed in his play and attitude (red cards, suspensions, twitter whining). You saw none of the attitude issues prior to the Liga MX offer being turned down. In retrospect, are we sure RBNY is better off having not sold Murillo and Kaku at the prices they were offered?