Which Teams Are Best Built for Postseason Success?

What causes teams to succeed in the playoffs? This is one of the debates in baseball most ridden with conventional wisdom, folksy tales, and grand assertions. Some claim that teams need to have playoff experience. Others focus on clutch performance, which usually coincides with whatever the person wishes to argue. A common argument, more cloaked in the language of reasonableness, is that teams that are more reliant on home runs than other ways of scoring underperform in the postseason. There are myriad reasons given for why some teams end up winning October, and most of them can tested for accuracy based on baseball history. I did a piece last year that looked at dozens of different team variables, and most of the explanations meant bupkis.

That doesn’t necessarily mean we throw our hands in the air and just assume teams are equally as good as they are in the regular season and go with that. There are significant structural differences between postseason and regular-season play simply due to the number of games and the increased number of off-days. Regular-season winning percentage is one of the few good predictors of postseason success; projections do even better. When I change the methodology in the ZiPS projections to focus more on a team’s frontline talent and the exact matchups and less on important regular-season things like depth, team strength becomes significantly more predictive of postseason success.

One of the best recent examples of this is the Nationals in 2019. Despite the 13-win regular-season advantage of the Dodgers, ZiPS projected their NLDS as a coin flip on the strength of the Nats being able to stuff so much of their team’s value into players who would be on the field. That was a projection that got a lot of pushback, but in the end, Washington won the World Series, basically riding the top of the rotation, a few really good hitters, and the two or three relievers that Dave Martinez could actually trust.

As I’m an obsessive tinkerer, I’ve done more work on the subject in the last year. Using the original methodology, I found a slight advantage for teams that were more reliant on home runs to score runs. After more research, I’ve found that the homer-reliance advantage becomes an even more significant indicator when you’re going against elite pitchers. There’s something that makes intuitive sense there; the best pitchers are hard nuts to crack, and you’re more likely to break them with a few homers. Just one example is Clayton Kershaw. His struggles in the playoffs are well noted, but it’s entirely due to home run rate; his BABIP, strikeout, and walk rates are nearly identical to the regular season. But it doesn’t matter what the logic is if the data doesn’t match; the tendency for homer-reliant teams to overperform in the postseason historically nearly doubles when looking at only the games in which the opposing starting pitcher had a seasonal ERA+ of 125 or better.

So, which teams get a postseason boost from structural design? Let’s crunch some numbers! To get this, I took the likely postseason rosters for each of the 15 playoff-relevant teams remaining (I left out the Giants, at 0.1% playoff probability) and used the regular-season model to estimate their expected winning percentage against a .500 team in a neutral park. Injuries are tricky at this point in the season, so educated guesses had to be made about player availability. For example, the Braves get half of Charlie Morton, and the Rangers get 20% of Max Scherzer. It was important to keep the roster design the same for regular season and playoffs so that we were looking at how the teams are currently built, not who gets what pitcher back next week (e.g. the Braves and Max Fried, who is currently unavailable).

I then recalculated everyone’s strength using the postseason model and ranked them by the change from regular-season to postseason projection. Let’s actually start with the non-playoff teams, both because I’m a cruel man and because it’s interesting to see which teams might have caused havoc in the playoffs if they had gotten there:

The Padres have been a bit of a train wreck thanks to their one-run and extra-inning performances, but they still had the front-end offensive talent to make teams uncomfortable, if their last-gasp attempt to make the playoffs had succeeded. And while this is arguably the worst Yankees team of the last 30 years, they still have Gerrit Cole and Aaron Judge, and even their mediocre hitters can still run into a homer from time to time.

The Braves come out the big winners using this methodology. The concerns that ZiPS had about the team are effectively neutralized in a postseason context. With Morton’s injury and 10 other pitchers currently on the IL, I’d be highly concerned about them fielding a pitching staff for six more months. For four weeks, that risk is much lower. Atlanta also has hit nearly 60 more homers than any other team in baseball, and the lineup itself is extremely solid from tip to tail. There’s a reason ZiPS currently has the Braves with 29% odds of winning the World Series, which is as large a percentage as I can ever remember it projecting before the start of the playoffs.

On the flip side, ZiPS is worried about Miami’s stunning lack of offensive talent. The starting pitching has always been the big concern for Baltimore in the projections, and while Kyle Bradish’s projections have inched up over the course of the season and the computer always liked Grayson Rodriguez and Dean Kremer, it still sees the top of the rotation as lacking compared to the competition. Arizona always fared better in ZiPS because of its depth rather than its top talent (with the exceptions of Zac Gallen and Corbin Carroll). Similarly, the projections saw the Blue Jays as safe more than explosive.

Is this a guarantee that the Braves and Astros will face off in the World Series? Of course not! We’re not playing the playoffs a million times but once, and when you have only chance, chaos reigns in playoff baseball.