How did LA rotation get better without Kershaw?

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When Clayton Kershaw returns to the mound on Thursday, it will have been nearly a month since he landed on the disabled list, his third straight season interrupted by injury. He's hardly the only Dodgers starter to have had a disappointing month; they've received only 1 1/3 innings in May from Hyun Jin Ryu (injured groin) and just 9 2/3 from Rich Hill (repeated blister issues).
For essentially the entire month of May, the Dodgers have been without 60 percent of their Opening Day rotation. (On Tuesday, they lost a fourth starter, when Kenta Maeda departed early due to a hip strain that sent him to the DL.) For a team that entered the month at 12-16 and eight games out in the National League West, that might have been enough to sink its season. But the Dodgers' rotation hasn't collapsed. Quite the opposite, actually. It's thrived.

After all that's happened, Dodgers starters have a 3.31 ERA, the fourth best in baseball. They have 5.9 Wins Above Replacement, which is tied for the sixth best in the Major Leagues. How are they doing it, without Kershaw, without the injured Julio Urías, and with limited contributions from Hill and Ryu? Let's explain.
1. They're missing plenty of bats
Dodgers starters have struck out 27.2 percent of the hitters they've faced, third in the Majors behind the Astros and the Nationals. In some ways, that's not surprising, since they haven't been outside the top five in that category since 2012. They whiff hitters every year, in large part because they have Kershaw every year.
This year, however, this hasn't been about Los Angeles' ace. The rotation has about missed bats from some unexpected sources. Just look at how many different Dodgers starters have accumulated strikeouts at an above-average rate.
Strikeout rates for Dodgers starters
31.1 percent -- Ross Stripling
31.3 percent -- Ryu
30.3 percent -- Maeda
30.0 percent -- Walker Buehler
26.5 percent -- Kershaw
23.1 percent -- Alex Wood
21.8 percent -- MLB SP average
21.7 percent -- Hill
15.7 percent -- Brock Stewart
Other than Stewart, a fill-in who has made two spot starts, every Dodgers starter has been at or above the league-average strikeout line. That includes solid pre-injury contributions from Ryu and Maeda, but the standout name here is Stripling, a swingman who'd made 16 starts for the Dodgers over the past two seasons and made his first 10 appearances this year in relief.

Stripling set a career high in strikeouts with seven, against the Reds on May 12. He broke it with nine vs. the Nats in Washington on May 19. Stripling broke that with 10 against the Padres on May 25. After an 8-2 win Thursday night against the Phillies, he's whiffed 35 with only two walks allowed in his past four starts. Stripling is doing it, in part, with secondary pitches. Only two regular starters have used their fastball less often.
2. They're generating a ton of soft contact
We define the line between "soft" and "hard" contact as being at 95 mph of exit velocity. The Majors hit .517 with a 1.029 slugging when the ball is hit at 95 and above; they hit .216 with a .254 slugging at 94 mph of exit velocity and below. It's a simply tremendous difference.
Dodgers starters, as a group, have allowed the lowest hard-hit rate in baseball, at 30.6 percent.

But what's more interesting is if we look at the 145 pitchers who have allowed 100 batted balls and see who's at the top of the list in terms of preventing hard-hit contact.
Lowest hard-hit rates in 2018
24.2 percent -- Matthew Boyd, DET
24.6 percent -- Stripling, LAD
24.6 percent -- Blake Snell, TB
25.2 percent -- Ryan Yarbrough, TB
25.7 percent -- Jacob deGrom, NYM
25.8 percent -- Carlos Martínez, STL
25.9 percent -- Kyle Freeland, COL
26.5 percent -- Buehler, LAD
There's Stripling, preventing hard contact more often than anyone else in the National League. There's rookie sensation Buehler in the top 10.
"Walker and Ross were sixth and seventh on the depth chart out of Spring Training," manager Dave Roberts said last week. "For those guys to play huge roles speaks a lot."

Dodgers starters also have the third-lowest walk rate in the game, so when you put it all together -- lots of strikeouts, few walks, elite hard-contact prevention -- you start to see the story here. Even without Kershaw for the past month -- as well as Hill and Ryu -- the Dodgers' rotation has stepped up. Here's how we show that.
3. They've been a top-five pitching rotation
You probably got that above when we said the Dodgers were fourth in ERA and fifth in WAR. We probably don't need to go deeper than that. But just to further the point, we have a pair of advanced stats to share that explain what we mean. First, we can show that they're fourth in wOBA, or Weighted On-Base Average, which is very similar to traditional on-base percentage except it gives more credit to extra-base hits than singles.
Lowest wOBA allowed by starting pitchers
.258 -- Astros
.272 -- Nationals
.277 -- Cardinals
.284 -- Dodgers
.290 -- Phillies / Indians
.314 -- MLB SP average
We can also show that the Dodgers are even better, second, in Expected wOBA, which attempts to strip out the effects of ballpark and defense to get to only the quality of contact and amount of contact, i.e. the things a pitcher has the most control over. (In both cases, Los Angeles is well behind Houston, which may end up with one of the greatest rotations of all time.)
In fact, we can look at the 138 pitchers who have faced 100 hitters this year, rank them by Expected wOBA (which, again, accounts for the quality of contact and amount of contact) and you'll see some wild names in the top 10. You'll see two Dodgers. Neither are Kershaw.
Lowest Expected wOBA by starting pitchers
.229 -- Justin Verlander, HOU
.240 -- deGrom, NYM
.241 -- Buehler, LAD
.241 -- Stripling, LAD
.254 -- Max Scherzer, WSN
.266 -- Charlie Morton, HOU
.267 -- Aaron Nola, PHI
.267 -- Gerrit Cole, HOU
.270 -- Sean Newcomb, ATL
.272 -- Chris Sale, BOS
The point isn't that Buehler and Stripling are actually going to be two of the five best pitchers in the Majors from this point forward, because they probably are not. It's to say that based on what we've seen so far this year, they've pitched like it. Looking at the other names on that list, it's clear that's not a leaderboard you can fake your way onto. 
No matter which stats you prefer to use, traditional or advanced, Dodgers starters have more than held up their end of the bargain, and they are doing so without a huge chunk of the expected rotation. In 26 games since their ace went down, Dodgers starters allowed a 2.99 ERA, seventh best in the Majors in that span. They've done it without the best pitcher in the game for nearly a month. Now, they get him back. It'll help, because he's Kershaw. But they've done more than well enough without him.