The 2021 regular season is officially in the books. Playoff baseball commences tomorrow night. According to FanGraphs, the Astros are the favorites to win the pennant. Fresh off winning the AL West for the fourth time in five years, their reward is a five-game series with the White Sox, the only other team in the American League that FanGraphs gives a greater than 10 percent chance of winning the World Series.

If the Astros are to reach the American League Championship Series for the fifth consecutive year, they’ll need to go through the AL Central champions in the American League Division Series. Only five teams in baseball finished with a better run differential than the White Sox. Given their prowess on the mound and their capabilities at the plate, they present a touch matchup for any club.

Hitting

• Batting average: .256 (5th in MLB)
• OPS: .758 (7th in MLB)
• Walk rate: 9.6 percent (4th in MLB)
• Strikeout rate: 22.8 percent (19th in MLB)
• Stolen bases: 57 (22nd in MLB)

Despite key bats such as catcher Yasmani Grandal and outfielders Luis Robert and Eloy Jiménez each missing significant portions of time throughout the season, the South Side’s offense was still a highly productive one. Now entering the postseason, Grandal, Robert and Jiménez are all in good health.

The White Sox finished the regular season third in Weighted Runs Created Plus (wRC+) and fourth in wOBA. Only the Astros and Nationals (???) posted a higher team OBP. But with that notable feat comes questions.

In terms of Chase rate, Chicago hitters ranked 22nd this year. However, in spite of their below-average plate discipline, they ranked 4th in Walk rate. At the same time, only Reds hitters saw fewer strikes per Zone%, but it’s nonetheless intriguing that several White Sox position players are at or near the top of the leaderboard regarding the difference between a hitter’s Walk rate and their Deserved Walk rate (dBB%), courtesy of RotoGraphs’ Alex Chamberlain’s Pitch Leaderboard.

In addition, the White Sox have been fairly reliant on productive ground balls. They’re third in the big leagues in ground ball rate, which perhaps isn’t inherently a terrible thing, but it’s never a good sign when the majority of the clubs that have similar percentages are some of the worst in the major leagues (Rangers, Marlins, Pirates, etc.). Moreover, there’s an anomaly in the equation.

On ground balls, the White Sox’ batting average is the fourth-highest at .255. But their Expected Batting Average (xBA) is the fourth-lowest at .230. The 25-point discrepancy is the most among all teams.

This isn’t to discredit the skill of premier hitters like shortstop Tim Anderson, who won the AL batting title in 2019, but it’s possible that an element of luck has artificially enhanced Chicago’s overall numbers, which could give way to regression. A league-high .310 BABIP only adds to the suspicion.

But be that as it may, the White Sox’ .321 Expected wOBA (xwOBA) was good for 12th in baseball, so no matter how they’re sliced, it’s at least an above-average offense. Just one that has produced better than expected numbers.

In any case, the uber-toolsy Robert learning how to hit big-league pitching (20.6 percent K rate) is a scary notion for the Astros and all opposing pitchers.

Pitching

• ERA: 3.73 (5th in MLB)
• WHIP 1.20 (5th in MLB)
• Batting average: .226 (3rd in MLB)
• Walk rate: 8.3 percent (10th in MLB)
• Strikeout rate: 27.1 percent (1st in MLB)

Perhaps no other matchup in this series will be more significant than the one between White Sox pitching and Astros hitters. No other staff has a higher Whiff rate than the White Sox, and no other lineup makes more contact than the Astros.

Unlike their hitters’ data at the plate, White Sox pitchers have produced airtight numbers on the mound. The pitching staff as a whole is fifth in ERA, fourth in Fielding Independent Pitching (FIP), third in xwOBA and first in K%.

The starting rotation has been one of the game’s finest in 2021. Lance Lynn’s 2.69 ERA is only outdone by his 2.59 Expected ERA (xERA). Lucas Giolito led the team in innings with 178.2 and did so with a 3.53 ERA and 3.29 xERA. Breakout years from Dylan Cease (93rd percentile K%) and Carlos Rodón (2.37 ERA) solidified the unit’s upper-echelon status.

As great as their collective and individual numbers during the regular season were, there is a problem that’s been brewing for weeks.

Rodón has been dealing with arm and shoulder issues, which has resulted in a substantial decline in his velocity. For much of the year, the former first-round pick had sat in the mid-90s and was able to reach back for more, but in his final regular season start last Wednesday — when he threw just 69 pitches — Rodón’s average four-seam fastball velocity was 90.9 mph. It was the bottom of what’s been a gradual descent.

Should the White Sox need to rely on their bullpen more than they did in the regular season, however, few other teams are better equipped. Closer Liam Hendriks spearheads a deep relief staff that posted the highest strikeout-to-walk percentage in the bigs as well as the lowest Skill-Interactive ERA (SIERA).

In the age where seemingly every team has at least one reliever who can reach triple digits, the White Sox bullpen is unrivaled in terms of fastball (4-seam, 2-seam, sinker) velocity, with a collective average of nearly 96 mph.

Against 96-plus heat, Astros hitters’ batted balls ranked 18th in wOBA and 11th in xwOBA.

Defense

• Fielding percentage: .982 (27th in MLB)
• Wild pitches: 84 (27th in MLB)
• Passed balls: 18 (29th in MLB)
• Stolen bases: 119 (30th in MLB)
• Caught stealing: 24 (12th in MLB)

Simply put, the White Sox are not good defensively.

As a team, their Defensive Runs Saved (DRS) over the 162-game campaign was minus-39, which ranked 26th. The Yankees are the only other playoff team in the bottom 10. Bizarrely, a pitcher led the White Sox with 12 runs saved: Dallas Keuchel. No other player made it even halfway to the former Astros starter’s mark.

Outs Above Average (OAA) paints a prettier picture, albeit one of mediocrity that pegged the White Sox 18th. Robert rates favorably in center field, but every corner outfielder on the roster that’s been trotted out does not. The Astros’ launch angle was the fourth-highest in the regular season.

The data in this article was compiled via Baseball Savant, FanGraphs and Pitch Leaderboard