The Dodgers certainly haven't "won the winter," so far as the headlines go, because they haven't been aggressive on Bryce Harper, a fact that's doubly disappointing because it certainly seemed like the trade with the Reds that sent Yasiel Puig, Matt Kemp and Alex Wood to Cincinnati was expressly set up for them to do exactly that. The catching swap of Yasmani Grandal for Russell Martin was a clear downgrade. Importing free agents A.J. Pollock and Joe Kelly were bets on health and talent, respectively, but the 2019 roster looks a lot like the 2018 roster.
That may not be exciting, but it's also not a bad thing. The Dodgers, six-time defending National League West champions, are projected to easily win the West again, picked to finish eight to 11 games better than the Rockies, depending on which flavor of projection system you prefer. They're going to be good, and that's in large part thanks to the fact that they're projected to have the best run-prevention unit in baseball, projected to allow just 3.87 runs per game. 

Projections are what they are -- educated, informed guesses, really -- but there's generally a good relationship between projections and outcomes, and it certainly makes sense enough that the Dodgers, Mets, Indians and Astros would have the best run prevention projections, and that the Tigers and Orioles would be pulling up the rear. 
(The numbers noted above are via the Steamer projection system at FanGraphs; looking at Baseball Prospectus' PECOTA system, which uses a very different methodology, the Dodgers are in a virtual three-way tie for best with the Astros and Yankees.)
This isn't out of character for Los Angeles, obviously. The Dodgers have allowed the fewest runs per game in the NL in each of the past two years. They've finished in the top five in each of the past four years. It's difficult to win this many division titles if you aren't doing a great job at keeping runs off the board. 
Dodgers' pitching runs per game ranks in MLB
2018: 3.74, first in NL, second in MLB
2017: 3.58, first in NL, second in MLB
2016: 3.94, fifth in NL, fifth in MLB
2015: 3.67, second in NL, second in MLB
(In 2014, they were 11th in the Majors; they were third in '13, fourth in '12, and haven't been below-average since the 91-loss '05 team.)
Maybe it's less impressive that they're projected to be the best run-prevention team in 2019 than it is that they've been doing it for so many years in a row. Regardless, you can expect more of the same, and there's more a full reasons why.
1. Because Walker Buehler may be baseball's next great ace 
It may be blasphemy to say it, but what if the great Clayton Kershaw is no longer the Dodgers' best starting pitcher? Maybe it's too soon to say that, and it says a lot about how wonderful Kershaw has been that we're worrying about his decline after a year in which he put up a sparkling 2.73 ERA -- though that was his highest mark since 2010. 
While concerns about Kershaw's falling velocity are real, he's still projected to be an above-average pitcher, and Buehler is projected to be his equal in 2019. It's not hard to see why, considering how dominant he looked at times in his 2018 season, considering that he just put up a 2.62 ERA in 137 1/3 innings. When we looked back at 2018's most dominant pitches, Buehler ranked in the top five for both his four-seam fastball and his sinker. 

Put another way, just look where Buehler ranks on the leaderboard of one of our most powerful metrics, Expected wOBA, a Statcast™ number that accounts for both amount of contact and quality of contact. There were 183 starters who faced 200 batters in 2018, and the Top 5 is more than a little impressive.
.232 -- Chris Sale, Red Sox
.236 -- Justin Verlander, Astros
.243 -- Jacob deGrom, Mets
.246 -- Max Scherzer, Nationals
.247 -- Buehler, Dodgers

(For what it's worth, we put our money where our mouth is by ranking Buehler as the 10th-best starter in baseball on MLB Network's Top 10 Right Now recently, ahead of names like Kershaw, Carlos Carrasco, Patrick Corbin and Luis Severino.)
2. Because they brought back two key lefty arms
It does feel like there's an impossible-to-define feeling in free agency that it's just not as exciting when a team brings back their own free agents as it is when they add new ones. For the Dodgers, we saw this two offseasons ago, when they retained free agents Justin Turner, Kenley Jansen, and Rich Hill, each of whom have contributed to the back-to-back NL pennants. 
This year, it was re-signing Kershaw for three more years, as well as welcoming back Hyun-Jin Ryu after he accepted the one-year qualifying offer. Other than Wood, every pitcher who made at least two starts for the 2018 Dodgers will return in '19.
That's not as exciting as, say, trading for Corey Kluber, but it's generally a good thing. The oft-injured Ryu threw only 82 1/3 innings, but they were spectacular ones, with a 1.97 ERA. Kershaw may not be the clear-cut "best pitcher in baseball" that he once was, but he's still expected to be a solidly above-average starter.
3. Because the projections buy into Kelly
We'll admit that Kelly doesn't have anything like the name value of his former teammate in Boston, Craig Kimbrel, or even that of Andrew Miller, Jeurys Familia and David Robertson, all of whom signed with new teams this offseason. 
As we investigated in-depth when Kelly signed with the Dodgers in December, this is a bet on talent, not just on the small-sample 13/0 strikeout/walk mark he put up in October for the Red Sox. 
Remember, this is what we wrote at the time: 
Obviously, you start with the aforementioned "great stuff," and it's not hard to see what's attracting the Dodgers here. Over 600 pitchers threw at least 100 fastballs, and Kelly's 98.1 mph average velocity was fourth best. Call it a 99th-percentile skill. Over 230 pitchers threw at least 100 curveballs, and Kelly was one of only six to average over 3,000 rpm of spin rate. Call that a 99th percentile skill, too.
This is the sort of thing that teams like the Astros look for, that raw skill that hasn't quite turned into reliable results. The Dodgers are betting they can get the best out of Kelly, and the Steamer projections agree, expecting a 3.21 ERA in 65 innings. 

4. Because they still have more depth than they know what to do with
All five Dodgers starters -- Kershaw, Buehler, Ryu, Kenta Maeda and Hill -- are projected to have an ERA below 4.00. So does Ross Stripling, a 2018 All-Star who might not make the top five right now. So does Julio Urías, who batted back from a serious shoulder injury to play a role in the 2018 run to the World Series. 
There are currently 118 pitchers projected to be worth at least one WAR, and no NL team -- and only the Yankees overall -- can top the seven names the Dodgers have on the list. That group doesn't include the relief quintet of Pedro Báez, Dylan Floro, Caleb Ferguson, Scott Alexander and Josh Fields, and even those guys combined for a 2.93 ERA in 276 1/3 innings.
It's true that not adding Harper or trading for Kluber or making a reality any other of the earth-shattering rumors we heard this weekend has left a sour taste in the mouth of Dodgers fans, and it's also true that the Dodgers required a one-game tiebreaker to top Colorado for the division last year. But "last season's record" isn't how you evaluate a team for the next season, and the Rockies, who lost Adam Ottavino, DJ LeMahieu and Carlos González (while adding Daniel Murphy), haven't really improved themselves this offseason. 
"The most important thing we have to do when the offseason starts is to critically assess the team from the year before," president of baseball operations Andrew Friedman said last week. "Not just how many games did we win, it's what was our talent level? At what we expected? Below, above? We felt we were much better than a 92-win team."
Friedman is almost certainly referring to the plus-194 run differential -- third in the Majors -- that had the Dodgers playing more like a 102-win team than a 94-win one. It doesn't guarantee 102 wins in 2019, and it certainly doesn't guarantee this is the year they get over the World Series hump. Another bat, like a Harper, would surely have done more to satisfy Dodgers fans. But on the mound, you can expect more of the same, which is to say: Expect another very strong pitching staff.