Took fitch down twice and maintained dominant position. Avaunt Diaz, BJ only had one single leg that Diaz nearly reversed, and then forced BJ to stay up. 
I wouldn't say he ahd an "easier" time, rather it seemed to be that he was trying more often.
Timing.
Nick's Sambo coach -
Diaz is better on his back than Fitch.
BlahBreh -Well if you took a deep breath and tried to grasp what he meant, as opposed to spouting off sarcastic D-bag responses, you would understand his comment. Midget.Tad Ghostal - Diaz is better on his back than Fitch.No way??????? Damn didn't know that, anyways what were we talking about Here? Takedown defense or jitz?
BJ might not have wanted to take Diaz down as much as he did Fitch....hence the comment. You self owned your stupidity on that response.
PiousDevil - situational, short term variance, imo.
Sufficently analogous to draw comps
Answer:
Nick knew BJ was not going to stand with him for long and would try the take down like he did against Fitch. Him training with Hughes and the "rumor mill" was that BJ would use his wrestling again.
On the other hand, Fitch had no idea BJ would take him down but would rather choose to keep his distance to stop Fitch's takedown.
Bj took him down easily at first. But I guess he gassed harder than in the fitch fight.
Shahanshah - Nick Diaz is a lot better then Jon Fitch
Lol no
He gassed getting hit 200 times in the body does that
BJ got Diaz down easily in the 1st.
The next time he tried he was totally gassed and shot a really weak takedown.
The surprise factor was huge against Fitch--I'm pretty sure if they fought again BJ wouldnt get him down
BJ fell in love with his stand up. If your not a wrestler those desperate takedowns aren't usually very effective.
BlahBreh -What the fuck ru talking about Bj did take em down and attempted too plenty of times after. So "Bj not wanting to take down nick" is retarded.
An I'm 6'2 not a midget
Mental Midget.
You clearly didn't grasp what the other poster was implying, and went off on a sarcastic douche response, making yourself look stupid in the process.
"Diaz is better off his back than Fitch" was a totally relevant, and valid point. If you had a brain you would have grasped that. Apparently it went right over your head...
Fitch tore rotator cuff .. 3rd round Fitch laid it down. Fitch said BJ trying to take him down threw off his game. 
BJ was beat up pretty good by the time he tried his 2nd time iirc. He got the first.
I dont think Fitch expected it...element of surprise.
He gassed, and the explosiveness he had in the first round just wasn't there.
Edlova - Fitch tore rotator cuff .. 3rd round Fitch laid it down. Fitch said BJ trying to take him down threw off his game.
BJ took fitch down in the second round too. Why is everyone regurgitating fitch's excuse like gospel?
Man, it surprised me too...
fitch didnt expect a takedowmn, diaz did