It appears that Jon Jones wasn't the first choice to coach The Ultimate Fighter 17 against Chael Sonnen. According to MMA Fighting, the coaching spot was first offered to Quinton "Rampage" Jackson. But he turned it down:

"Forget TUF," Jackson told MMAFighting.com on Thursday. "I'm not interested in that." "I don't want to fight Chael. He's the kind of fighter that I don't want to fight. He's a boring fighter that just wants to hump people."

The article states that Sonnen was very interested in coaching against and fighting Rampage, but Jackson wanted nothing to do with it. And apparently Dana White has confirmed this was the original plan as well. Jackson has been even more outspoken than usual in recent days, asking White for bouts against Glover Teixeira and Forrest Griffin amongst others. He also went out of his way to insult UFC matchmaker Joe Silva, but he's backed off that a bit. He commented on Silva's upcoming hernia surgery:

"I wish him a speedy recovery, even though we don't see eye-to-eye. I wish no ill will on anybody."

Rampage vs. Sonnen would have worked well for TUF. Chael wouldn't be jumping the line at light heavyweight, and the two men would likely create some compelling TV. It's kind of funny that this has come out now though, considering the way Dana pushed Jones vs. Sonnen originally. White made it seem like the combination made complete sense and it was the plan from the very start. Apparently not.