Speaking to Radio Sport's D'Arcy Waldegrave on the eve of the Highlanders clash, Umaga remained confident he was the right man to lead the franchise.
"I suppose I'm seeing some players grow in terms of their game understanding. Trying to get those consistent effort performances has probably been the biggest thing," Umaga said.
"We know we're laden with talent and potential. It's actually making sure we have the work ethic around that. And I believe we've seen that."
The Blues' season - and his tenure as coach, since taking over from Kirwan 2 years ago - can not be deemed a failure, Umaga said.
"Yes, in terms of our outcomes this season we haven't started well but it's a bit early to be saying things like that.
"We've still got the opportunity to make the top eight, so in terms of that no, not at all. We're still in the hunt."
Umaga refused to be drawn on increasing speculation he had already signed a new deal with the Blues, that would see him remain at the helm regardless of results this year.
"I'm just concentrating on what I can control and that's the performance of these guys every week," Umaga said.
"That's what I enjoy and that's what I'm here to do. All that talk is just that, and obviously you'll find out in due course [whether a contract has been signed]."
The 44-year-old former All Blacks captain and midfielder admitted the Blues' recent results have not been easy to process.
"You do question yourself when things aren't going well, like in every walk of life. But you've got to have belief in what you're doing, and making sure that the process that you're going through, you're ticking all those boxes," Umaga said.
"Outcomes are great and that's what everyone is looking for. Yet, you can only really have so much control over that on the day."
He believes he hasn't lost the support of the players or the Blues boardroom - despite the deafening silence from the club's executives.
"You're always looking at yourself in terms of how you're going.
"I've got a good support group at home. I've been well supported here by the club, by the players, staff and the admin-istra-tion. That makes it a lot easier to turn up every day and excited about what you do."