It caught veteran point guard Shaun Livingston off guard.
"It's tough. Lawrence was obviously a voice, so that's the hardest part," Livingston said. "I don't think any of us saw this coming."
The Nets -- who were without the injured Deron Williams (ankle), Paul Pierce (hand), Jason Terry (knee) and Andrei Kirilenko (back) -- were then drubbed by the Nuggets, losing for the 11th time in 14 games.
"[We're] soul-searching here," Kevin Garnett said after the loss. "We were trying to figure out how to patch this thing up, how to get this thing together; there's a lot of moving parts to this. ... I don't think anyone around here is having fun, and losing is definitely not fun."
Garnett also has known Frank since he was an assistant with the Celtics in 2010-11.
"There's a lot of moving parts around here, and we are trying to adjust to it," Garnett said when asked about the Frank demotion. "That's how I am going to answer that."
"I think at this point, we are trying to figure out who we are and fix this," he later added. "We are at home getting beat by 30, 40 points, and that's not want we want. That's not even close to what we predicted where we wanted to be. We just want to understand, and like I said, there's a lot of things going on here, but no excuses."
Frank, who was head coach of the Detroit Pistons for the previous two seasons, has a relationship with Kidd dating to his time as an assistant under Byron Scott on the New Jersey Nets' coaching staff when Kidd arrived in a trade in 2001. The Nets went to back-to-back NBA Finals in 2002 and 2003.
Frank replaced Scott and was Kidd's coach from 2004 to 2008, ranking as the Nets' all-time leader in victories. Originally, Kidd had his coaching staff set up with Frank orchestrating the defense and Welch handling the offensive duties.
When the Nets went with Prunty as the interim coach in the first two games, Frank and Welch remained in their defensive and offensive coordinator-like roles, respectively, ostensibly for continuity.
But the Nets have had anything but continuity, as they have been ravaged by injuries and chemistry issues that also extended to the coaching staff. The Nets (5-13) had lost a total of 37 games due to injuries to six players going into the Denver game. Joe Johnson has been the only starter to start every game this season.
Defensively, the Nets were surrendering an average of 102.4 points per game, sixth-worst in the NBA, entering Tuesday night's game.
Frank's spot next to Kidd on the bench will instead be filled by Prunty, who has worked in the league as an assistant with four other teams (San Antonio, Dallas, Portland and Cleveland) and serves as a coach internationally with Great Britain.
"We'll be coaches, that is who we will be," Kidd said of who will handle the defense and offense moving forward. "There is no one doing offense, no one doing defense. We will take the responsibility of being coaches. That is how it will be set up."
Information from ESPNNewYork.com contributor Mike Mazzeo was used in this report.