So many things can get in the way -- randomness, regression, injuries, the Washington Nationals, etc. But the Dodgers and Cubs enter 2018 with the distinct possibility of doing something unprecedented in the National League -- meeting three straight seasons on the NL Championship Series stage. It's happened just once in the American League, when the Yankees beat the Royals three straight years from 1976-78 (the Royals finally got a measure of revenge in '80).
It can happen this season if the Dodgers and Cubs, who have traded LCS victories the last two years, live up to the projections. Now that the Cubs have added Yu Darvish to their starting staff, Steamer's projections have both clubs at an NL-best projection of 94 wins. Baseball Prospectus' PECOTA system sees more separation -- 99 wins for the Dodgers, 92 for the Cubs -- but those are still the top two marks in the NL.
The above has the impatient among us, here at the start of Spring Training, thinking about how these clubs might stack up in a potential rubber match. So with all apologies to the Nats and the rest of the NL clubs in clear position to contend in 2018, let's do a little tale of the tape with these two Senior Circuit stalwarts.

Rotation
We'll start here in the wake of the Darvish news, which effectively augmented the Cubs while depleting the Dodgers, who were only going to bring back Darvish if they could shed some other salary (i.e. the $43.5 million owed to Matt Kemp over the next two years).
Even without Darvish, the Dodgers are projected by FanGraphs to get more Wins Above Replacement (WAR) from their starting staff (18.3) than the Cubs are (16.9). But much of that projection is wrapped up in some guy named Clayton Kershaw (5.8 projected WAR), who has been limited to 48 starts over the last two seasons with back issues. For the sake of context, the fourth-highest projected WAR among Cubs starters is the 2.7 mark attributed to Kyle Hendricks, and the Dodgers don't have anybody other than Kershaw with a projection that high.

The Dodgers rely on Kershaw and depth. They opt for quick hooks and a rotating cast -- methods that make sense in the modern bullpen-oriented, injury prone climate. They have upside in top pitching prospect Walker Buehler and in the potential return of Julio Urias from shoulder injury.
The Cubs, meanwhile, have more of what you'd call an old-fashioned (and yes, it seems weird to be saying this about a Joe Maddon-managed club) starting five, in that we can write it down on paper today -- Jonathan Lester, Darvish, Jose Quintana, Hendricks and Tyler Chatwood -- and reasonably see it sticking. Chatwood's a serious upgrade candidate with the move from Coors Field, which makes him a really good No. 5. And swingman Mike Montgomery is solid insurance.
Edge: Cubs, because sometimes there's nothing wrong with being old-fashioned

Offense
It would be fruitless to list projected lineups here, because one of the biggest strengths of both of these ballclubs is the flexibility derived from a depth of quality position players. So let's just list all the guys from each club that we can reasonably be expected to get at least 300 plate appearances and the Weighted Runs Created Plus (wRC+) (a good barometer of offensive impact, with 100 considered league average) projections forecast for them by Steamer:

The Bryzzo Souvenir Co. is expected to churn out another stellar season, but, beyond them, the Cubs seemingly have a great deal riding on Schwarber having a full season akin to that 69-game sample we saw in 2015, as opposed to another year in which a high homer rate is offset by an inability to get on base otherwise. The Dodgers -- even with projected regression from Taylor (who had a surprising 126 wRC+ last year) have more guys projected to have what you could consider significantly better-than-average (120 or higher) seasons.
That said, the Cubs scored 5.07 runs per game last year to the Dodgers' 4.75, and the casts really haven't changed.
Slight edge: Cubs, who are projected by FanGraphs to score 0.2 more runs per game than L.A.

Defense
We have a hard enough time calculating defense, let alone projecting it. But again, because the cast of characters hasn't dramatically been altered, last year's Defensive Runs Saved tallies are worth citing here:
Dodgers, 68; Cubs, 24
A caveat here is that the more we see of the Russell/Baez pairing up the middle, the more it's clear that it's one of the best defensive double-play duos in baseball. And the Cubs are just a year removed from being heads and tails the best team in baseball on the DRS scale. But I'll lean toward the 2017 tallies here.
Slight edge: Dodgers

Bullpen
The Dodgers have a dominant closer in Kenley Jansen and some questions about who will set him up. The Cubs have a lot of strong setup types but lack a proven closer. The differences in these two bullpens were probably the biggest separator in the 2017 NLCS, with the Dodgers in the midst of a 28-inning scoreless streak from their relievers and the Cubs running Wade Davis into the ground.
With the Cubs having poached Brandon Morrow from L.A. (in addition to adding Steve Cishek), the scales have shifted a bit, though the obvious question is whether Morrow will have any hangover effect after pitching every game of the seven-game World Series. The Dodgers haven't had many acquisitions this offseason, but they made a trade with the Royals for lefty Scott Alexander, who very quietly accrued a 73.8 ground-ball rate in his first full season in the big leagues last year. In fact, Alexander is projected by FanGraphs to be worth the same WAR (1.1) as Morrow in '18.
Edge: Dodgers, because having clearly one of the best closers in the game is a pretty good tiebreaker

Prospect help
This is important as the game skews younger and younger. Just look at the unexpected impact Bellinger had on the Dodgers last year or how essential Schwarber was for the Cubs in this group's first foray into October in 2015.
We already mentioned Buehler's potential in the Dodgers' rotation or perhaps the bullpen. His special stuff has him at No. 13 on MLB Pipeline's Top 100 prospects list going into the year. And it's also pretty likely we see outfielder Alex Verdugo (No. 33), a disciplined hitter, this year. Beyond that prominent pair, there's power hitter Edwin Rios and his fellow infielder Matt Beaty among the young guys in the Dodgers' system that could get a look this year.
The Cubs' only contributions to the Top 100 are guys they traded (Gleyber Torres, Eloy Jimenez), but reliever Dillon Maples, catcher Victor Caratini, starter Jen-Ho Tseng and outfielder Mark Zagunis are some guys who could be important depth options for them this year.
Edge: Dodgers, because of the upside involved with Buehler and Verdugo

Flexibility
This kind of plays into prospect help, but the basic idea is this: Which team is in the best position to address whatever needs arise by midseason? Because the Cubs parted with so many pieces in trades the last couple years, the Dodgers simply have the deeper farm system right now. Both teams are in a similar projected payroll range (around $180 million to $185 million), but the Dodgers have extra incentive to stay under the $197 million threshold to reset their luxury-tax penalty (after going over the threshold five straight years). So that might limit them slightly, but the strength of their system still puts them in a great spot to make a big-ticket acquisition, if need be.
Edge: Dodgers

Front office
They're both brilliant, but really all Theo Epstein has left to accomplish in the world of sports is a Cleveland Browns Super Bowl.
Edge: Cubs
Manager
Did Dave Roberts and Maddon make questionable pitching decisions in the last two World Series? Yes, they did. Would you be happy to have either of these modern-minded men and effective communicators as the skipper for your favorite club? Yes, you would (or at least, you should).
Edge: Push

Conclusion
The Cubs have won consecutive NL Central titles, and the Dodgers have won five straight in the NL West. Both of these clubs play in strong divisions that will pose a challenge in the bid to repeat, and both are strong enough to fend off those challenges. But while the Cubs have clearly had the more exciting offseason, I'll give the Dodgers the edge here ever so slightly (I don't necessarily think it's a seven-game gap, as PECOTA surmises) based on what I feel is superior depth and flexibility.
That said, I'd rather watch them settle this on the field in another NLCS.
Slight edge: Dodgers