Both agreed that Castro overstepped and hurt his campaign when he sparred with former Vice President Joe Biden and even questioned the 76-year-old's memory.
Boothe said she thinks Castro's attacks on Biden "will leave a bad taste" in the mouths of Democratic voters and that Castro, 44, spent more time swiping at Biden than talking about his own campaign.
Williams echoed her sentiments, saying Castro's was "vicious" toward Biden.
"If you want to do something like that, you have to do it with skill. This was too much of a bludgeoning," he said.
Biden and Castro duked it out over who was properly “fulfilling the legacy” of the 44th president, specifically on health care.
Castro claimed that his vision of a “Medicare-for-all” type of plan was more true to former President Barack Obama’s health care philosophy than Biden’s plan, which would leave private insurance alone while providing a public option.
“I’m fulfilling the legacy of Barack Obama, and you’re not,” Castro said.
“That’ll be a surprise to him,” Biden fired back.
Castro also took a shot at Biden’s memory, accusing him of contradicting himself about whether Americans would have to buy into a public health care option under his plan or if they would be automatically enrolled.
"You just said two minutes ago they would have to buy in. Are you forgetting what you said two minutes ago?" Castro asked.
As her winner of the debate, Boothe chose Sen. Elizabeth Warren, D-Mass., explaining that she's been "consistently good," avoiding missteps each time to continue her upward momentum in the polls.
Williams said that Biden was the winner of the debate because he "came out stronger" and took the offensive on the health care issue, which was the dominant issue of the debate.”
He also noted that Beto O'Rourke, who made waves with his vow to take assault weapons away from Americans, had a "good" night.