Tambellini, in his fifth season as GM, was replaced by former Oiler coach and vice-president Craig MacTavish.
"I'm an impatient guy," MacTavish told a news conference at Rexall Place, sitting beside Kevin Lowe, the Oilers president of hockey operations.
"We're at the stage in terms of the cycle of our hockey club right now that we have to do some bold things. We have to expose ourselves to some semblance of risk to try and move the team forward in a rapid fashion," said MacTavish.
"We've got primary pieces here but we've got to add some depth to help these young players."
MacTavish was the Oilers coach from 2001 to 2008, then left hockey to acquire an MBA at Queen's University. He returned to the Oilers last summer as the senior vice-president of hockey operations.
With Lowe and MacTavish at the podium was former Oilers assistant GM Scott Howson.
Howson was recently fired in February as GM of the Columbus Blue Jackets and now takes over MacTavish's old role as senior vice-president of hockey operations.
Tambellini was not at the news conference.
The announcement came after the Oilers were expected to compete for a playoff spot in the lockout-shortened 2013 NHL season, but instead are all but mathematically eliminated from the post-season.
Heading into NHL action Monday night, the Oilers were 12th in the Western Conference standings with a 16-18-7 record, eight points behind eighth-place Detroit.
"I for one really had hoped that we'd be a little more advanced than we are now," said Lowe.
"And because careers are short and opportunities for achievement don't come along very often, we feel strongly that it is important that we make some changes right now."
Lowe said a decision on Tambellini was in the works for awhile, but said the team's current five-game losing streak, including a listless 4-1 loss Saturday to the Calgary Flames, didn't help.
"Losing five in a row, how we lost, where we are — all those things go into the decision," said Lowe.
"If we're going to do something, then why wait."
It has been seven miserable years for the Oilers since they pushed the Carolina Hurricanes to a seventh and deciding game in the 2006 Stanley Cup finals.
The team hasn't made the post-season since and three previous seasons have seen the Oilers at or near the bottom of the NHL.
The miserable finishes have translated into acquiring a core of talented young scorers through the draft like Nail Yakupov, Ryan Nugent-Hopkins, Taylor Hall and Jordan Eberle. The Oilers also added free agent slick-handed defenceman Justin Schultz this year.
MacTavish said the Oilers still need better, bigger, and more rugged role players to support the young guns.
He said when it comes to deals, all players are up for grabs, but said when it comes to the core players, "we would part with those assets very begrudgingly."
MacTavish gave a word of encouragement to head coach Ralph Krueger.
"I think he's done a great job with our young players," said MacTavish.
"What we need to do is give the coaches better tools to compete."
MacTavish, Howson and Lowe have been with the Oilers in management and coaching capacities to varying degrees throughout the seven-year playoff drought.
Lowe got heated when one reporter pointed that out to him rather pointedly.
"How are fans are going to be reassured that the group that left the mess that Tambellini couldn't quite clean up is now going to be cleaned up by the guys who left the mess to begin with?" asked the reporter.
"In terms of the group that messed things up, you're talking about the group that had a team one period away from winning the Stanley Cup?" Lowe shot back.
"Seven years ago," said the reporter.
Lowe pressed on. He said after coming close to the Stanley Cup in 2006 Oilers management decided to try to keep the core group together. When that failed three years ago, they overhauled the roster and started from scratch.
"Are you saying to me you're getting impatient after three years?" challenged Lowe.
"There's one other guy I believe in hockey today that is still working in the game that has won more Stanley Cups than me. So I think I know a little bit about winning."