Editor's Note: (Todd Graham is the director of debate at Southern Illinois University. His debate teams have won five national championships and he has been recognized three times as the national debate coach of the year. Follow him on Twitter. The views expressed in this commentary belong solely to the author. View more opinion at CNN.)

(CNN) One of the things to look for when judging a presidential debate with ten people on stage is anything that makes a candidate stand out. By that measure, two candidates had memorable debates and one had a particularly regrettable experience Thursday night.

A-

Pete Buttigieg

Buttigieg was steady. His positions on education, Medicare, and China all seemed reasonable and his confidence in his positions never wavered. Mayor Pete's answer on climate change was the best I've heard over these two nights of debates: he told us that rural Americans are part of the solution, not part of the problem.

Todd Graham

But it was his lecture on hypocrisy and religion that was the show stopper. I've never heard a candidate directly call out the religious right as strongly as Buttigieg (who's a Christian) when he said that a political party that thinks "God would condone putting children in cages has lost all claim to ever use religious language again." Damn.

Unfortunately, his trouble with solving racial inequity in South Bend was the worst part of his debate. But I give him credit for his honesty. Asked why they still had issues with race and policing, Buttigieg said "because I couldn't get it done."

A-

Kamala Harris

The line "America does not want to witness a food fight. They want to know how we're going to put food on their table," worked for Harris. But that isn't why Harris was impressive. She was real. And believable. And she set a tone that was just perfect. On immigration, she was excellent. On racial inequality, she was outstanding. Plus, Harris was a good debater. She absolutely made Biden look foolish on racial issues, busing, and working with racist senators in the past. She absolutely beat Mayor Pete on his failings with his own African American community. The senator had both style and substance.

But it wasn't a perfect night for Senator Harris. When she finally said she'd reverse Trump's tax cuts to pay for her own plan, she missed the mark. After all, we didn't have those tax cuts two years ago, and we couldn't afford all the Democratic proposals then. Harris also rambled on climate change for a bit. Finally, her closing was too scripted and memorized.

B

John Hickenlooper

He may not be the most exciting candidate on stage, but after listening to all his answers, I would have moved to Colorado under his former governorship. Hickenlooper did the best job tonight defending his time in office.

C+

Andrew Yang

Here is my standard for the candidates who barely spoke: Based on what they said in the debate, if they did get more time, would they have been better than either Biden or Sanders? Yes, for Yang. In the short time that he got to speak, he presented himself better than either of these better-known rivals, like when he took aim at "trillion-dollar tech companies."

C

Marianne Williamson

This grade surprises me, too. But I'm not changing my mind. I liked her entire first half of the debate. Sure, she's odd, but I found it refreshing (odd doesn't mean stupid). And her closing was true to herself as she directed her words at President Trump: "Mr. President, if you're listening, I want you to hear me, please... I have a feeling you know what you're doing. I'm going to harness love for political purposes. I will meet you on that field. And, sir, love will win."

C-

Bernie Sanders

He was strong in his typical areas such as climate change, and he gets points for referring to immigration problems as "hemispheric." He also was on point in attacking Trump and pushing back on Chuck Todd by rejecting the premise of another banal one-word question-and-answer response.

But Sanders was off his game on health care for all. How would it work? Public support. But how will that happen? Sanders didn't explain how the middle class specifically will do under his proposals. Plus, he blew right by the answer on how he'd govern, if the current Supreme Court overturned Roe v. Wade. It was an uninspiring performance.

D

Michael Bennet

He began with an uninspired answer on healthcare, arguing that a universal healthcare plan is what the country needs. Sure, universal healthcare might be a defensible policy, but it needs a better defense than the simplistic one he gave: Finishing what Obamacare started and having a public option is a good plan. While he went on to give a personal anecdote about his own health, there was little said that hasn't been said before.

D

Eric Swalwell

He interrupted too much. And his "pass the torch" line, directed at the experienced Democrats, only worked because Sanders and Biden could have performed better -- not because Swalwell proved he should be the torchbearer.

D

Kirsten Gillibrand

She began interrupting people during the first question. The first dang question. And this continued until it was her turn to speak. That's when she sniped, "No, it's my turn," which she said without a hint of irony. Other than Beto O'Rourke's Spanish speaking during night one of the debates, this was the worst first impression of any candidate.

D-

Joe Biden

I don't know what the problem is -- whether it's a lack of preparation, terrible coaching, pressure of being the frontrunner, or he's just lost a step -- but this was Joe Biden's worst debate I've ever seen. His nonverbal cues made him often appear confused. His willingness to stop in the middle of a sentence when the timer ran down was awkward to the point of embarrassing.

Biden stumbled over Obama's name one time and didn't give a full-throated defense of his time as Obama's VP until an hour and thirty minutes into the debate. Unforgivable. Plus, Biden got hammered on several issues. His answers meandered without a central focal point and while they somewhat improved over time, the appearance he projected tonight was the exact opposite of what he needed. And then there was the moment when Sen. Kamala Harris called out Biden for his comments about formerly working with segregationist Senate colleagues. Biden had an opportunity to defend himself, but he fumbled it.