When it was pointed out to Theo Epstein over the weekend that the Chicago Cubs’ farm system, for the first time in Epstein’s tenure as president of baseball operations, does not have a single prospect ranked in the top 100 by “Baseball America”, Epstein delivered the perfect comeback: “And it’s the first time we can call ourselves defending world champions.” The assembled media members chuckled, but Epstein wasn’t joking.

“That’s a lot better,” he added, “than having some top-100 prospects.”

With baseball trending more in the direction of youth every year, the Cult of the Prospect can at times seem all-powerful and all-encompassing, with top-prospect lists, organizational rankings and detailed scouting reports telling us who is best-positioned to win in the future.

But that isn’t the same as winning in the present, and Epstein, by trading away the Cubs’ two best remaining prospects last week — slugging outfielder Eloy Jimenez and right-handed pitcher Dylan Cease — in a four-player package to land lefty Jose Quintana from the Chicago White Sox, demonstrated again why prospects matter in the first place. Not to fill top-prospect lists, but to fill big league rosters — whether to push a World Series contender over the top, as in 2016, or to rescue a would-be contender still trying to find its stride, as in 2017.

“The best farm system — you can see it by watching your big league team, whether they’ve been promoted or you’ve traded them away to bring talented players here,” Epstein said. “That’s what we’re looking for.”

After spending his first few years in Chicago meticulously building the Cubs’ farm system into one of the best in the game, with the big league team bottoming out with 197 losses in 2012 and 2013, Epstein spent the past two watching the brightest jewels of that farm system turn into big league assets, either with the Cubs or, via trades, elsewhere.

Last summer, shortstop uber-prospect Gleyber Torres was the central piece of the package that brought closer Aroldis Chapman from the Yankees. Slugging first base prospect Daniel Vogelbach helped them land lefty Mike Montgomery. This winter, outfielder Jorge Soler brought them Wade Davis, who has capably replaced Chapman as the Cubs’ closer.

And this part should not be forgotten: another top Cubs prospect, outfielder/second baseman Ian Happ, earned his promotion to the big leagues in May, and has turned into a crucial piece of the Cubs’ everyday lineup. A sweep of the Baltimore Orioles over the weekend lifted the Cubs above .500 again, at 46-45.

“Ian Happ doesn’t count as a prospect anymore,” Epstein said, “but I’ll take a 22-year-old coming up and hitting 13 [homers] in his first 2½ months in the big leagues any day of the week, out of your farm system.”

Jimenez, 20, was Epstein’s last big card to play, a consensus top-15 prospect with game-changing power and a towering ceiling, but he was also several years from impacting the big league team with a skill set that more or less mirrors that of Kyle Schwarber — the young slugger who, despite an unexpected detour to the minors earlier this season, remains part of the young core of position players around whom the Cubs have built their club.

“If we thought less of this position-player group as whole, with Schwarber a big part of it, it would’ve been harder to trade Eloy,” Epstein said. “It’s not as if there’s no scenario in which we could’ve found a spot for him to play. That’s not the case. But we think this group is going to be here and be together for years to come. It allowed us to entertain the notion of trading him if the right deal came along.”

The Cubs no longer have one of the best farm systems in the game, but one good draft and a few solid international signings could go a long way toward fixing that. Restocking a farm system is far easier than winning a World Series.

“I have all the faith in the world that we’re going to continue to draft and sign players to restock our farm system,” Epstein said. “ … And I should say there’s lots of talented players still down on the farm who we believe in, who are going to play for the Cubs. It’s been a really good year for pitching development in our system. We’re excited about certain guys on the way here.”

Meanwhile, the White Sox, the Cubs’ crosstown rivals, are at a stage similar to the one the Cubs occupied four years ago, stockpiling top prospects and building a farm system that is the envy of the game. This winter’s trades of Chris Sale (to Boston) and Adam Eaton (to Washington) brought back significant hauls of young, highly regarded prospects, and the Quintana trade brought them more.

Three of the top 20 prospects in the game and seven of the top 100, according to Baseball America, reside in the White Sox’ system, all of them — aside from recent signee Luis Robert, from Cuba — acquired by trade in the past year. Everyone in the game can see they have the makings of a future powerhouse.

But that is not the same thing as a current powerhouse, or even a surefire future one.

Perhaps one day, if everything falls right for the White Sox, they can aspire to having a farm system with none of the top 100 prospects.