Trump’s either smart or lucky that he didn’t because, hoo boy, this would have been a roundhouse.

“We were kind of hoping he would [attack]. We were all set to really go after him,” Carson campaign manager Barry Bennett told me in the spin room after the debate. According to Bennett, Carson planned on telling Trump: “I saved 15,000 lives in the operating room. And you don’t appreciate my service, but I wouldn’t trade a single one of them for all of your money. Money’s not important to me. It’s not what’s important to most Americans.”

But the opportunity to deliver those lines never came as Trump refrained from criticizing Carson to his face during the two-hour debate. “It’s kind of Dr. Jekyl and Mr. Hyde. When he’s alone at night with his Twitter account, he can say some pretty nasty things. But then when he’s around people it’s all nicey-nice,” Bennett said. “I don’t know. He’s an entertainer.”

Trump was surprisingly subdued throughout the debate, with two exceptions. One was when he channeled the feelings of millions of Republicans watching at home and said of Kasich, “I don’t need to hear from this man.” The other was when he piped up to grumble that Fiorina kept interrupting people, which was a dumb thing to do given that Kasich was a much worse offender than Fiorina and Trump’s already been accused of sexism for singling her out for her looks. Apart from that, though, he was Mr. Congeniality. Even after the debate, he couldn’t say enough nice things about the moderators. And then, when he went on “Morning Joe” this a.m., he … praised the competition. I hope they bring back the real Donald Trump soon because the new, gracious, mature version is frankly weirding me out:

“I don’t want to be critical, I like him,” Trump said during a nearly 45 minute appearance on MSNBC’s “Morning Joe” Wednesday. “Ben and I have gotten along well over the period of time. I’ve become friends with a lot of the people that are up there.”…

“I would let him operate under a friend of mine, not necessarily me but a friend of mine,” Trump said, laughing.

“Will you let him run one of your companies?” Scarborough repeated.

“Sure. If you’re talking about a company, sure,” Trump said.

He’s going to let Ben Carson, who suffers from a “pathological disease” for which he should be taking medication, run one of his businesses? What?

What changed all of a sudden to make Trump call off the dogs? With anyone else I’d suspect that he’s squeamish about face-to-face confrontation, but this is Trump. It smells like someone convinced him that going hard after Carson is too risky at the moment, when conservatives are circling the wagons around him to protect him from media misinformation about his biography. Either that or Trump’s decided that he needs to sand down some of his sharper edges and project a more “presidential” comportment, to the extent that he can. People in Iowa and New Hampshire are paying attention now and deciding whether to spend their vote on this guy or laugh him off once and for all as a stunt candidate before settling on Rubio or Cruz. The less he comes off like an insult comic, the more plausible he seems as a nominee.

Either that or the guy’s suddenly gotten very low energy. Exit question: Who is this man and what have you done with the real Trump?