Warren and Sanders did nothing to exacerbate those tensions like Cruz did. They didn't necessarily defuse them, either.
Instead, the case for Clinton from both Warren and Sanders basically boiled down to this: Clinton is right on the issues that are important, and she's better than Trump.
Warren spent much of her speech dismantling Trump — something at which she has become adept. Toward the end, she spent some time running through the issues on which Clinton is right. She punctuated each issue mention by saying, "And we're with her."
"Hillary will fight to make sure discrimination has no place in America, and we're with her," Warren said.
"We believe that no one — no one — who works full time should live in poverty," Warren said. "Hillary will fight for raising the minimum wage, fair scheduling, paid family and medical leave, and we're with her. "
Sanders did much the same thing, running through a litany of issues. Many of his Clinton comments began with "Hillary Clinton understands" or "Hillary Clinton recognizes" and were contrasted with Trump's position on the issue.
At the end of Sanders's speech, he finally provided the kind of personal, full-throated endorsement of Clinton that had been absent from the speeches to that point.
"Hillary Clinton will make an outstanding president, and I am proud to stand with her tonight," Sanders concluded.
Both Warren and Sanders played things smartly. Litigating the sins of the DNC and being too defensive about Clinton risked inflaming the passions of Sanders supporters in the room — some of whom made their voices heard even as their liberal heroes were speaking.
They smartly combined their mentions of Clinton with mentions of issues that have broad liberal support, making it harder for the crowd to boo and sow discord. After all, how can you boo a higher minimum wage, action on climate change and Democratically appointed Supreme Court justices?
And Sanders provided his most passionate support of Clinton at the very end of his speech, when the crowd was bound to cheer loudly.
None of which is perhaps surprising. Sanders and Warren were given a tough task on Monday night, and neither of them would have been well-advised to tell Sanders backers that they were "being ridiculous," as comedian Sarah Silverman so bluntly said earlier Monday night. Doing so would have clearly been a recipe for a Cruz-esque show of disunity. Sanders backers could have turned on either of them quickly.
And it bears noting that the somewhat-tempered support is hardly just a Democratic thing: Republicans spent much of their convention last week deriding the alleged horrors of a Clinton presidency rather than providing character witnesses for Trump.
Nor was it entirely necessary for Warren and Sanders to tell Sanders supporters to stop "being ridiculous." While delegates are a vocal bunch, polls show as many as 9 in 10 Sanders backers are onboard with Clinton for the general election — a strikingly fast rallying effect that is actually faster than it was after a lengthy 2008 primary between Clinton and Barack Obama. The delegates in the room were a different story, yes, but after they officially vote for the party's nominee this week, it's kind of a moot point.
Still, it's important to note that the divisions in the Democratic Party weren't totally healed on Monday night. Warren and/or Sanders arguably could have expended some political capital to make that so, but they opted to live to fight another day for progressive causes.
Which is probably what they had to do, given the very real tensions in the room they were speaking in.