By Bruce Levine–

(CBS) Watching the manner in which the Cubs have put together their core of young players has been impressive. While holding on to all of them would be nice for the Cubs, that function of player development and building a winning team isn’t really practical.

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Some of the Cubs’ organizational weaknesses were exposed in the humbling NLCS defeat at the Mets. When it was over, an observer could get the feeling — for the first time — that some of that youthful Cubs inventory could be wearing different home team jersey as early as next season.

Entering his fifth year as the baseball boss on the North Side, Theo Epstein will have to look at the organization’s pitching needs and lack of depth. Epstein and general manager Jed Hoyer must decide which path to take in the offseason. Ideally, the Cubs would add via free agency, but that would come with the loss of draft pick(s). The more prudent way to go is use a duplication or two among the position players as chips for shoring up the weakness on the mound.

The Indians are an example of a team that matches up well with the Cubs in the trade market. Cleveland is seeking right-handed hitting and, according to league sources, would love to acquire outfielder Jorge Soler from Chicago. Soler, 23, was slowed by injuries in 2015, hitting .262 with 10 homers and 47 RBIs in 101 games, but he flashed his potential, power and plate discipline in a monster postseason.

Would the Indians part with 25-year-old right-handed starter Danny Salazar?

That one-for-one deal would be hard to imagine, as it’d be more likely that other players are involved too. Salazar had a breakout 2015 season after a slow start, going 14-10 with a 3.45 ERA and 1.13 WHIP. Salazar averaged 9.5 strikeouts per nine innings and had a strikeout-to-walk ratio of nearly 3.7-to-1, quality of which are quality marks.

Cubs infielder Starlin Castro, 25, has upped his value as a trading chip. He was almost traded in late August after losing his starting shortstop job, only to rebound with a monster September in which he hit .426 with a 1.202 OPS. With a number of interesting starting pitchers to dangle, the Padres have shown interest in Castro in the past. Right-hander Andrew Cashner, a former Cub, is a name worth keeping an eye on.

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Epstein admitted Thursday that holding on to all of his young players may not be realistic, as much as he’d like to.

“I would love to have our entire position group back,” Epstein said. “The competition is good, the depth is great.T he depth is important. That is a significant competitive advantage, giving us solutions at the ready when something goes wrong. It gives us a competitive advantage to mix and match for that opposing pitcher. It is a huge advantage but also might not be possible (to retain everyone). We have some other areas we need to address (pitching). We may be forced in a situation where the right move is to take away somewhat from that position player group. That would be to add pitching. I don’t know. I would love to keep that position player group intact.”

The bottom line is the Cubs can’t move forward, in the long term, with three shortstops and — depending on the progression of minor leaguers such as Albert Almora and how the free-agent market plays out — perhaps four outfielders who need everyday at-bats. One or a few really good young players will need to be moved properly on the trade market to help get better pitching and defenders in the mix.

“I am not sure it will be possible,” Epstein said of keeping this entire young core together. “The best case is preserving all of our depth and impact talent and growing with it. I am not sure that will be a reality. I would love to make that happen.”

The Cubs’ greatest challenge now will be to evaluate their own talent properly — and then that of others — before pulling the trigger on a deal.

Could Soler be a 40-homer slugger? What’s Javier Baez’s most realistic projection? Can a pitcher like Salazar be the difference in pushing them into the World Series in the coming years?

They’re all tough questions for the Cubs to contemplate before the trading and free agent season begins in early November.

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Bruce Levine covers the Cubs and White Sox for 670 The Score and CBSChicago.com. Follow him on Twitter @MLBBruceLevine.