The numbers tell an interesting tale.

In a single day last week, the average age of the members of Prime Minister Justin Trudeau's cabinet dropped from 52 to 50 – making it one of the younger cabinets in Canadian history.

Three ministers, all in their 60s, were shuffled out of cabinet, replaced by much younger colleagues. While those close to Trudeau say it was all about geography and preparing for incoming U.S. President Donald Trump's administration, for many Liberals, it was also a sign of generational change.

Ever since he became leader of the Liberal Party in 2013, Justin Trudeau, 45, has slowly but surely been transforming the Liberal Party, fulfilling the pledge of renewal he made when he sought the leadership. One by one, older veterans of the party have been replaced by younger successors — from party officials to political aides and cabinet ministers.

The Liberal Party today is arguably now younger than the party Trudeau inherited three years ago. However, that has also led to grumbling among some veteran members of the party – often baby boomers.

Immigration, Refugees and Citizenship John McCallum, 66, was shuffled out of Trudeau's cabinet and named Canada's ambassador to China. (Sean Kilpatrick/Canadian Press)

Privately, some who served in previous Liberal governments confide that their calls weren't even returned when they applied to join Trudeau's government, leaving them with the sense the new administration considered them past their best-before date. Others, who have given up weekends and time with their families to knock on doors and campaign for the Liberals over the years, feel their experience and their expertise are no longer really wanted or required.

"They have a problem with people over 45 or so," said one long-time Liberal organizer who traded anonymity for candour.

What about 'institutional memory?'

"They're very bright for the most part, but it wouldn't be so bad to have players with some institutional memory. The only time they listen to people like me is when the information I have to offer is essential."

Those close to Trudeau, however, dismiss any suggestion that older MPs and party supporters are being sidelined.

"I just don't think that's fair or true," said one senior source, who spoke to CBC News on condition they not be named.

While some Liberals who worked in previous governments didn't get hired, it had more to do with skill sets than age, they explained, pointing to a handful of ministerial aides with experience in previous federal Liberal governments.

Minister of Employment, Workforce Development and Labour MaryAnn Mihychuk, 61, moves from cabinet to the back benches. (Adrian Wyld/Canadian Press)

"I think the world changed a lot between the time there was a Liberal government last time and now," they said. "Facebook and Twitter didn't exist, to start. It was a pretty disruptive nine years in terms of the skill set required for politics."

"I think that it may be that a lot of the people who had worked in previous Liberal governments had skill sets devoted to that time and era that we felt were less applicable to this one."

On the party side, the Liberals need people who understand the technology that has transformed campaigns and politics, they said.

Generational change a staple of politics

"The old way of doing politics, of political campaigns, has gone the way of the horse-drawn carriage."

Foreign Affairs Minister Stephane Dion, 61, was shuffled out of cabinet Tuesday and is leaving active politics. (Adrian Wyld/The Canadian Press)

Veteran Liberals like Peter Donolo, former aide to former Liberal Prime Minister Jean Chrétien, says generational change is a normal part of every political party.

"I think it is a change, generational renewal, and I think it is a positive thing," said Donolo, discussing the cabinet shuffle. "I think it is the case in terms of not just elected officials but the PMO, the minister's offices — it is a new generation."

Chrétien's first cabinet included some veteran ministers that were destined from the start to give way to younger colleagues, he said.

"Back in my time with Mr. Chrétien…in 1993 he put a number of quite experienced ministers in senior portfolios with the full knowledge and intention that they weren't going to last the whole mandate," Donolo explained.

"He did that for two reasons. One is he wanted the kind of experience to be able to hit the ground running. Secondly, he wanted to be able to show others in the caucus that there was a chance, there was a hope that they could get into cabinet."

Big contrast to Trump 'geritocracy'

Ironically, one of those young MPs brought into cabinet following the 1995 referendum, was Stéphane Dion, who was shuffled out of cabinet Tuesday.

Quito Maggi, president of the polling firm Mainstreet Research, says millennials are beginning to outnumber baby boomers. (Submitted by Mainstreet Research)

Trudeau's cabinet is also in sharp contrast with Trump's, which Donolo described as a "geritocracy."

"The chief (Canadian) interlocutors with the Trump administration are going to be this feisty, ball of fire, four-foot-five woman who is on Putin's no fly list. There's a defence minister who is a turbaned Sikh. An immigration minister who is a Muslim born in Somalia. A French-Canadian trade minister. I think it's great."

"The contrast is tremendous. I think one is a last gasp of a certain kind of politics and culture and the other one is the future."

Pollster Quito Maggi, president of Mainstreet Research and a former Liberal Party organizer, said Trudeau's changes are in line with the changing demographics of Canada as millennials aged 18-34, who voted overwhelmingly for Trudeau, begin to outnumber baby boomers, who are now 53 and older.

"As we go on, 2015 was when millennials eclipsed the boomer generation in population. By 2019, it will be a pretty significant shift," said Maggi.

"When it comes to voting, certainly those voting populations will even more exceed what it was in the last election, so appealing to those groups continues to make more and more sense."

People like Trudeau's principal secretary Gerald Butts are very well aware of Canada's changing demographics, tweeting after the cabinet shuffle Tuesday that the median age in Canada was now 40.6.

Median age of Canada: 40.6 <a href="https://t.co/5PAWQMrgPp">https://t.co/5PAWQMrgPp</a> —@gmbutts

Maggi said several factors go into the selection of cabinet members, including regional representation, gender and ethnic background, but he predicted many Liberal MPs past age 53 can probably forget about making it into Trudeau's cabinet in the future.

"If you're a boomer in Ontario or Quebec – forget about it."

Boomers have the money

However, Maggi says there's also a risk for Trudeau if Liberal boomers start to feel eclipsed by millennials and the 35 to 52-year-old members of gen X.

"There could be a little bit of a danger. Baby boomers still represent the second largest chunk of the population in the Western world, including Canada, and by far represent the biggest chunk of wealth and, by extension, influence and power so that carries some risks for Mr. Trudeau."

While no Liberal boomer has ever become prime minister of Canada, Donolo points out that sometimes it's just the way things go.

"I think baby boomers, we have gotten used to being the centre of attention and we've kind of been perennially adolescents and I think it is a bit of a rude awakening to see the parade moving on."

Elizabeth Thompson can be reached at elizabeth.thompson@cbc.ca