The Chicago Cubs just won the World Series, their first in 108 years. The way this team is constructed, though, they might not have to wait long for another one.

A few facts about this team, and why they’re going to be tough to take down over the next few years.

Chicago Playing Time Allocations Hitters PA MLB Rank OPS Rank 25 and Under 2,434 3 0.807 3 26-30 2,411 21 0.763 7 31-35 1215 19 0.746 12 36 and Over 275 13 0.641 13 Pitchers TBF MLB Rank OPS Rank 25 and Under 214 30 0.484 1 26-30 3129 14 0.621 1 31-35 1813 10 0.659 1 36 and Over 777 4 0.663 6

It’s no secret that the Cubs have some of the best young hitters in baseball, but it is exceptionally rare for teams with this many young hitters to win it all. The last World Series winner with to give at least 2,400 plate appearances to players in the 25 and under category was the 1971 Pirates; unsurprisingly, the Pirates won 57% of their games in the 1970s, finishing first or second in their division in seven of the next eight years.

But even that Pirates team wasn’t really this Cubs team. The star players on that team were 31 year old Willie Stargell and 36 year old Roberto Clemente. The ’71 Pirates had some really good young position players, but as a group, they got +17.1 WAR from their young hitters; the 2016 Cubs got +18.4 WAR from their young hitters, despite using 400 fewer plate appearances.

To put that +18.4 WAR from 25 and under hitters into comparison, let’s look at the last 70 years of baseball, which takes us back to 1947, avoiding the years World War 2 messed with the game’s demographics. During that span, only seven teams have gotten more production from their young hitters than this year’s Cubs team.

But even that undersells how good this group is. 25 and under is an arbitrary bucket I just used because that’s how the Play Index splits their age groups, but the Cubs actually didn’t have any 25 year old hitters this year, so using that bin compares them to other teams with older hitters included. Using our leaderboards, you can dial in more specific age brackets, and if you go 24 and under, you’ll see the Cubs still have +18.4 WAR, you’ll see only three teams have gotten more production from that group in the last 70 years than this Cubs team.

This is an historically great group of young hitters. Having some great young hitters doesn’t guarantee anything — for instance, the 1978 Expos rank atop the young hitter WAR leaderboard, and then had a two year run of 90 win teams that didn’t reach the World Series, before fading — but it’s the best place to start building a franchise. The 2015 Mets were exciting because of their young arms, but as 2016 showed, arms break, sometimes all at the same time.

As the table above shows, this Cubs team was extraordinarily reliant on young hitting, but not at all reliant on young pitching. And while the age of the pitching staff is the likely weak spot in any dynasty talk, the fact that this team doesn’t have a lot of expected value tied up in the most fragile asset you can have speaks to the solid base they have in place. The Cubs middle-aged and older pitchers aren’t going to keep pitching this well forever, but there’s a lot less risk in this kind of pitching staff than in one that is heavy on young arms.

And while Kris Bryant and Anthony Rizzo are obviously the cornerstones, it’s the depth of young positional talent that really makes the Cubs scary. With any group of players, you’re going to have some guys who go the wrong direction, or never develop as expected, but there are just so many reinforcements here. The team only got a half season out of Willson Contreras this year, and he’ll almost certainly play a bigger role on the 2017 Cubs team. Kyle Schwarber missed the whole season, essentially. Javier Baez was still a part-time player. Jorge Soler is still around and still talented. Albert Almora is around as an interesting outfield option for the future, especially if he ever learns how to take a pitch.

It’s not just Bryzzo and Russell, and because of that depth, the Cubs should be able to field high-quality athletic line-ups capable of sustaining something like this level of performance for a while. We can’t hand wave away the contributions of older players like Dexter Fowler and Ben Zobrist, but by and large, there isn’t much reason to expect the Cubs offense or defense to take a big step back any time soon.

The pitching staff is where the questions lie. John Lackey isn’t going to be this good for much longer. Jon Lester is aging. Jake Arrieta is a year away from free agency, and based on his reported asking price, is probably only going to spend one more year with the Cubs. The bullpen, as we just saw, has some question marks surrounding the health of their best regular season arms, and the group looks a lot weaker if Pedro Strop and Hector Rondon aren’t 100% next year.

But the Cubs are a high-revenue franchise that just set themselves up for a significant windfall, thanks to the revenue boost that comes from winning a World Series. This is a team that can afford to spend money on free agent pitching to supplement their young core. It’s the kind of team that can afford to take on contracts if need be, because the cheap young hitters give them plenty of budget room to add quality veterans at market prices.

This roster is something close to the ideal way you’d want to build a team for the long-term, and we may not have even seen the Cubs at their best yet. They won 103 games and the World Series, but there’s enough guys on this team that can still get better that this might just be the start of the run, not the very top of the mountain.

Of course, baseball can happen. The Cubs should be thrilled they got one when they had a chance, because they might not get another one. Baseball can be fickle. But looking at how this Cubs team is structured, there’s a real chance that this was just year one of the kind of dynasty we haven’t seen in baseball since the Yankees owned baseball at the end of the 1990s.