Starting pitching tends to get a lot of emphasis in the postseason, deservedly so. One starter might get 20% of a team's starts in the regular season, but in a five-game series, a team's ace can pitch twice, doubling his impact.
A team's most important pitcher might not necessarily be its best pitcher. With that said, here are the most important starting pitchers for each team in the division series:
St. Louis Cardinals: Jack Flaherty
In a Cardinals-Braves series full of quality starters, Flaherty is the only true ace on either squad. Even after pitching the final game of the season to give St. Louis the division title, Flaherty is lined up to make two starts. Flaherty's 4.1 fWAR in the second half topped the National League and sat behind only Justin Verlander in all of baseball. In each of his last 12 starts, he's gone at least seven innings and given up one or no runs. When he takes the mound in the second game of the series, he'll be pitching to either give the Cardinals a commanding 2-0 lead or fighting to prevent the Cardinals from going down 2-0. If that's not the most important game of the series, it will be Game 5, when Flaherty is scheduled to pitch again.
Atlanta Braves: Mike Foltynewicz
Foltynewicz had an awful start to the season and was demoted for much of the summer, but he has come back strong. In his past nine starts, Foltynewicz has 48 strikeouts against 15 walks and just five homers allowed after giving up 18 home runs in his first 12 outings. He might not have pitched as well as his 2.48 ERA would indicate, but he was still one of the better pitchers in the league during that time. He's likely to draw a start against Flaherty. If the Braves can steal that game, they will be in great position to advance to the NL Championship Series.
Los Angeles Dodgers: Clayton Kershaw
Through the middle of August, Kershaw was having a very strong but mostly unnoticed season due to the very low ERA of Hyun-Jin Ryu and the emergence of Walker Buehler. After shutting down the Marlins on Aug. 14, Kershaw sported a 3.21 FIP, a 2.63 ERA and a 3.7 WAR, which ranked seventh in the National League. The Dodgers didn't have much to play for the rest of the way, but his 6.11 FIP, 4.46 ERA and 13 homers in his last seven starts is cause for concern. Kershaw doesn't need to have his old Cy Young form to put on a good show for the Dodgers, but the Nationals can match them with rotation firepower, and a good start from Kershaw can establish the tone of the series or be a pivotal turning point, depending on where manager Dave Roberts slots him in.
Washington Nationals: Max Scherzer
Scherzer started the wild-card game and gave up three runs on two homers and also offered up three walks. He did strike out six batters in five innings to show off some of the old Scherzer, but he hasn't been the same since returning from his back strain. In eight starts, including the wild-card game, Scherzer has pitched 43 innings and struck out 60 batters with only 11 walks. Unfortunately, he's also given up 10 homers. Patrick Corbin and Stephen Strasburg look set to match up with two of the Dodgers' three aces, but the Nats need Scherzer to keep the ball in the park if they want to go toe-to-toe with Los Angeles.
Houston Astros: Zack Greinke
The Astros went 58-19 this season in games started by Verlander, Gerrit Cole or Greinke, and a merely very good 49-36 in games started by other pitchers. The key for the Astros is to not get to those other pitchers. If Verlander and Cole get the job done in the first two games, it will be up to Greinke to shut the door. While we've seen pitchers go to the Astros and get better, Greinke has remained his typical very good self -- throwing his changeup and slider just a tiny bit more and giving up a few more fly balls, but the strikeouts, walks, homers and runs have all been the same since joining an already great staff.
Tampa Bay Rays: Tyler Glasnow
After Charlie Morton pitched in the wild-card game, the Rays are going to need another starter to step up. Glasnow isn't necessarily the ideal choice given that his innings will likely be limited, but the former Pirate does have the highest upside to shut down a great Houston lineup for a few innings, at least. Glasnow missed most of the second half of the season, but in three September appearances, he struck out 16 of the 38 batters he faced and allowed just seven of those batters to reach base. If he can do that for four, maybe five frames against the Astros, he might help the Rays steal a game in their attempt to upset the American League West champs.
New York Yankees: Luis Severino
The Yankees' rotation is thin and filled with question marks. The biggest low-ceiling, high-reward option they have is 2018 ace Severino. He's made just three starts this season and pitched only 12 innings, but he could be counted on for an important start against the Twins. His three appearances have been a mixed bag, with a decent four innings against the Angels, a nine-strikeout, no-walk performance against the Jays, and a three-inning, four-walk start to close the season against the Rangers. Severino has barely even pitched with this season's new ball, and he's going against a homer-happy Twins club, potentially in homer-happy Yankee stadium.
Minnesota Twins: Jose Berrios
The 25-year-old righty looked like his solid season might be fading after a rough stretch in August, but Berrios finished strong. In his final four starts, Berrios struck out 26 batters in 26⅔ innings with just six walks and a 3.08 ERA. Expect a heavy dose of four-seamers up and curves down against a righty-heavy Yankees lineup. In Berrios' last four starts, roughly two-thirds of his pitches to righties were four-seamers or curves. Getting through the lineup twice without incident could go a long way toward finally getting his team past the Yankees.