"I'm here to play senior games and help this team win; I'm not here to make up the numbers," De Boer said.
"We'll be bringing our experience, and that mindset and attitude to every session to push the boys."
Mzungu says he hasn't given any thought to those who doubted the Giants' decision to give him another chance.
"It doesn't faze me in the slightest. I know internally we're really driven and we think we can help this group," Mzungu said.
"I know I need to work incredibly hard, and if an opportunity presents itself then I'm sure I'm up for the challenge.
"I treat it as a real opportunity at a team that is really on the rise and driven for success."