FWIW I believe the cubs need better player development but it’s worth noting the nats won with the oldest roster and the least homegrown players.
Just as has been the case throughout baseball history, there will never be a single way to win. Teams have won spending a ton of money. Teams have one through player development. Teams have won because of ace-level starting pitching. Teams have won because they have the best offense. Teams have won because of their bullpen. Etc., etc., etc.
The player development situation is important because it allows you to be most efficient with your financial resources and it's effectively the business continuity/disaster recovery plan for the organization. If you can fill a roster with cost-controlled young talent, that's outstanding, but those guys can be trade bait as well....plus, if you can fill a handful of positions cheaply, then you can afford to go spend huge money on a couple truly elite players.
What burned the Cubs is that they had their run of early draft picks and did pretty well with that (and flipped some vets into good young players like Arrieta, Strop, Hendricks, Russell, Rizzo), but when some guys stagnated in their development and the bulk of the high-end pieces of the pipeline were dealt in a small handful of deals, they were left with no depth. There were no cheap arms to come up and fill the 5 spot when Darvish was hurt and Chatwood wasn't effective. They haven't had a decent string of bullpen filler arms at the AAA level. All of which puts more burden on spending and FA pickups when they've already been carrying dead or relatively dead money on Heyward, Chatwood, Morrow, Darvish (1st year, he earned his keep last year).
The Cubs don't necessarily have to have an elite farm system (though that would certainly be nice). It's not as critical as it is for teams like the Twins, Padres and Rays, but they can't be living in the bottom 5th of MLB. If they can get to a point where they're developing talent well enough to hang in the upper half of baseball, they should generally have enough talent scattered around to always have some top 100 guys and some organizational depth. That would mean that in any given year, they have some trade chips and the ability to supplement the ML roster with a couple kids. You'll always have some slight ebbs and flows where maybe you have a particularly good draft or two or fall back a bit when 2-3 top prospects hit the bigs or are traded around the same time, but if the solid base is there, they shouldn't stay in the lower third for long.
