The Red Sox defense will be the key factor in the ALCS

The Red Sox are back in the ALCS for the first time since 2018, and have already gone much further than anyone expected. In a way, everything is gravy. But at the same time, we are certainly rooting for the deepest run possible, and to that end the Astros seemed like the worst matchup. Obviously they are an outstanding team simply on the merits of making it this far, and doing so for five straight years. And there’s also the matchup history this year between the two, when Houston didn’t just beat Boston five out of seven times, and didn’t just do so handily, but did so early in the year with the Red Sox rolling heading into each of those series (which were within a two-week span). Your mileage may vary on how much to take into account things that happened in June, but that was really the first time in the season when the Red Sox looked beatable.

And really, looking more ahead than behind, there are specific things about this matchup that just do not really work out well for the Red Sox. They were underdogs against the Rays, but it wasn’t as bad of a matchup in hindsight, and I think a lot of it was that the Rays swing and miss a lot, putting less pressure on a Red Sox defense that is anywhere from below average to terrible. That’s not going to be the case for Houston.

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Early in this run of success for Houston, the Astros struck out at a high rate, but have seen that come down precipitously in recent years, perhaps for different reasons including the sign-stealing elephant in the room for both teams in this series. But whatever the reason — and there’s no concrete evidence of cheating this season, even if accusations is part of the deal if you get caught previously — the Astros put the ball in play. A lot. Their 19 percent strikeout rate was the lowest in baseball this year, and many of their top hitters carry good-to-elite strikeout rates. Among the 262 players with at least 300 plate appearances this year, four Astros are in the top 15 in strikeout rate, and another is in the top 50.

That’s a troubling matchup issue for all teams because, of course, putting balls in play will lead to more success than striking out, but it’s particularly an issue for this Red Sox team. Their defense is frankly just not very good, and we saw in the second half that misplays can be extremely costly. Pretty much every defensive metric says they are in the bottom half of the league, with both UZR and DRS ranking them 19th in baseball this year, while OAA (Statcast’s defensive metric) ranks them as literally the worst defensive team in baseball. They have the greatest opportunity for success, perhaps more so than any other team in baseball, when their pitchers are missing bats. There is no team against whom that is more difficult than Houston.

The Red Sox are going to have to be vigilant in ways to counteract that, both in lineup decisions and as well as positioning. For the former, Alex Cora may have to think about Kyle Schwarber’s presence in the lineup, particularly against lefties. Alex Verdugo has sat in those situations at times, but his defense in left field would be better than Schwarber’s, and like we said it’s a different calculus in this series than it may have been against Tampa Bay. And with respect to positioning, the Astros put the ball in the air a lot, but they’re also in the top third of the league in pull rate and the bottom third in opposite field rate. Every little edge is going to be important here, and with so many balls in play the Red Sox need their defenders in the right spots to take away these hits.

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Mistakes on defense are going to be especially costly in this matchup, too, because this Houston offense doesn’t just put the ball in play. They punish teams for making mistakes, and they have the best overall offense in the game. They go seven deep with hitters who range from very good to elite, and often their seventh hitter is Kyle Tucker, who had the third best wRC+ in all of baseball in the second half. Put another way, there aren’t many breaks in this lineup, and giving them free baserunners is going to come back to bite you more often than not. They’re hard enough to slow down without those free runners.

And then on top of that, as we all know the Red Sox bullpen has some issues when it’s called upon for too many innings. They got big performances out of the bullpen for long appearances from guys like Tanner Houck and Nick Pivetta, but that’s easier to do schedule-wise in a five-game series than in a seven-game series. Now, there is greater importance on starters going as deep as possible, and the last thing Red Sox starters need is innings being extended because of misplays defensively.

It goes without saying that defense is always important, which again is something we saw over and over again with this Red Sox team. But going up against Houston in particular, it becomes even more crucial. Nobody puts the ball in play as much as the Astros, and perhaps nobody can make you pay for your mistakes as much as them either. The Red Sox defense, on the whole, is bad, but we’ve seen instances of them playing above their true talent in that respect for weeks at a time. If they can’t find that magic again in this series, it’s not hard to see Houston pulling away early in some of these games and ending this magical run.