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Friday night in Houston, the 2021 American League Championship Series begins with Game 1 between the Boston Red Sox and Houston Astros. This is a rematch of the 2018 ALCS, which the Red Sox won in five games, and the third time these two teams have met in the postseason in the last five years (the 'Stros swept the Sox in the 2017 ALDS). Here's how you can watch Game 1.

"I'm enjoying this. I am enjoying the group. I think we are clicking at the right time. Those guys are having a blast. This is what it's all about," Red Sox manager Alex Cora, Houston's former bench coach, said Thursday. "... It doesn't matter how you get here. It's just a matter of what you do from here on, and we're prepared for it."

The Astros led baseball with 5.33 runs scored per game this year and the Red Sox weren't far behind them at 5.12 runs per game. They were the fourth-highest scoring team in the game. Offense tends to decrease in the postseason because teams run their top arms out there every day, though the ALCS has a chance to be reasonably high scoring given the two teams and the two ballparks.

A few years ago the Astros popularized the art of pitching up in the strike zone, particularly with high spin four-seam fastballs. They went about generating that spin in unsavory ways (i.e. foreign substances), though the strategy was very effective and it inevitably caught on around baseball. Elevated fastballs are a great swing and miss pitch and the Astros embraced them fully.

The pendulum is starting to swing in the other direction now. Sinkers are returning to prominence -- Logan Webb just dominated the Dodgers for 14 2/3 innings in the NLDS with sinkers -- and the Astros are again at the forefront. Setup man Kendall Graveman, staff ace Lance McCullers Jr. (currently injured), and Game 1 starter Framber Valdez are all extreme ground ball pitchers.

Sinkers and the like are generally thrown down in the zone to get ground balls. I mean, that's the whole point. It's difficult to elevate a pitch down at the knees as it is. Throw a pitch with movement down there, and it's even tougher to get the ball airborne. Houston's pitching staff had the fifth-highest ground ball rate in baseball (44.7 percent) because they pitch down in the zone so well.

The Red Sox may be uniquely equipped to counter the "pitch down in the zone" strategy, particularly against Graveman and Valdez (and McCullers should he pitch in the ALCS). Several of their hitters are excellent low-ball hitters, and by low ball we mean pitches in the bottom third of the strike zone. Here are some numbers against pitches in the lower third of the zone:


Batting averageSlugging percentageExpected weighted on-base average

Bobby Dalbec

.302

.674

.450

Rafael Devers

.328

.608

.448

Enrique Hernández

.286

.581

.393

JD Martinez

.344

.557

.364

Kyle Schwarber*

.292

.562

.343

MLB average

.279

.438

.309

* Includes time with Nationals

Expected weighted on-base average, or xwOBA, is a catch-all metric that estimates how a hitter should have performed based on exit velocity, launch angle, things like that. Sometimes good contact leads to outs and bad contact leads to hits. This weeds that out and just looks at the contact quality. xwOBA is scaled to regular old on-base percentage, so .400 is great and sub-.300 is bad. 

In terms of xwOBA, the Red Sox have two of the nine best low-ball hitters in baseball in Dalbec and Devers, and Hernández is a top 35 hitter against low pitches as well. Devers is a fantastic all-around hitter, and my mental image of him is golf shot home runs, like his go-ahead ninth-inning homer in Game 162 to give the Red Sox home field advantage in the Wild Card Game.

On the flip side, Xander Bogaerts and Alex Verdugo are Boston's weakest low-ball hitters. Bogaerts hit .261 with a .345 slugging percentage (.313 xwOBA) against pitches in the bottom third of the zone while Verdugo hit .211 with a .320 slugging percentage (.290 xwOBA). Catcher Christian Vázquez has a .240 xwOBA against low pitches because of weak contact.

Point is though, five-ninths of Boston's regular lineup excels at punishes pitching down in the strike zone. That could be especially problematic for Valdez on Friday night. He's a sinker/curveball/changeup pitcher who uses the sinker and changeup down in the zone, and likes to back door the curveball to righties. Here is Valdez's regular season pitch location heat map:

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Framber Valdez likes to keep the ball down in the zone, generally. Baseball Savant

The brighter the red, the more pitches in that location. Valdez typically lives at the knees, which is generally an excellent place to work -- Valdez had a 3.14 ERA this season and by far the highest ground ball rate in baseball (70.3 percent, Webb was second at 60.9 percent -- but not necessarily against this Red Sox lineup. They'll reach down and drive low pitches.

The good news for the Astros: Valdez faced the Red Sox twice during the regular season, and held them to only two runs in 14 1/3 innings. He struck out eight and 10 in those two starts, his two highest strikeout totals of the season. Boston's ability to punish pitches down in the zone didn't help them the two times they faced Valdez previously this year.

Of course, those two starts came way back in June, before the Red Sox added Schwarber and before Hernández really took his game to another level. Adjustments will be made on both sides, and even then, it's impossible to predict individual pitches and swings. Players still have to execute and occasionally things go wrong during the course of a game. That's baseball.

"You can make some small adjustments on it, keep working it, but you don't want to get away from what's worked for you because that's when you're not going to be able to have success in moments like this," Valdez said Thursday. "I'm going to go out and throw all my pitches with intensity like I always have. Four-seam, two-seam, the changeup, curveball. Intensity and attack the strike zone, but I'm not planning on changing my game plan at all."

In the grand scheme of things, the ALCS will feature two high-scoring offenses and potentially some sketchy middle relief. On a more micro scale, the Red Sox have a lot of excellent low-ball hitters, and several of Houston's top pitchers are most effective down in the zone, Valdez specifically. It is the game within the game, matching your strengths to the other team's weaknesses.