Projecting players is always a difficult, error-filled practice, but it's even more difficult after a season of only 60 games. It would be a mistake to consider a projection for a player as something written in stone like your blood type or your birth date. Projections are like an endless puzzle in which you never really find out the "right" answer and every tiny bit of data shifts the direction you expect from a player. For players in a season with a relatively tiny number of games, postseason performance has more relevance than usual in setting expectations.
That postseason stats don't "count" in a player's record is an odd quirk stemming from the lack of organized postseasons during professional baseball's formative seasons. The proto-World Series matchups of the 1880s were informal exhibition matches that had to be negotiated between teams, and even the first modern World Series of 1903 was simply a voluntary event agreed to by the owners of the Pirates and the (Boston) Americans.
With the World Series being the official championship of the American League and National League (Major League Baseball wasn't really a single legal entity until just 20 years ago), these games are considered the most important by players and fans. So, we have the strange circumstance of Hank Aaron's 755 career home runs not including the three homers he hit in the 1957 World Series that helped the Braves defeat the Yankees. Why wouldn't performance in the most crucial games against the toughest opponent be taken into account? It's like a world champion skier not putting their Olympic gold medal on their résumé.
Be that as it may, postseason stats do generally help us make more accurate projections. How a player hits or pitches in the most difficult situations gives us additional information about a player. It requires a bit more work -- you have to account for the mixture of opponents more than in the regular season -- but useful information should be used wherever possible.
I started using postseason data in 2010 after researching the predictive value of projections with postseason data versus projections without and found a small but consistent boost in accuracy from their utilization. I emphasize the word small, simply because the number of postseason games is generally drowned out by the number of regular-season games. But even in a normal year, this has value. One example I like to point to is Daniel Murphy, whose three-year WAR projection in ZiPS increased 25% just from his 2015 postseason heroics. ZiPS projected he'd be worth three years and $29 million before the postseason and bumped that to $36 million afterward -- and he subsequently got three years and $37.5 million from the Nationals.
This year, for the teams that made it deep into the playoffs, postseason at-bats and innings pitched form a very large percentage of 2020 contributions for players. For some players, this new information is absolutely crucial. While Clayton Kershaw's 4-1 record and 2.93 ERA in the postseason don't change how we view him as a player, these 2020 postseason games can move the projections for a player with less experience or one about to hit free agency significantly.
As you might have guessed, we'll now look at some of these players, the nine who saw their projections improve the most thanks to the 2020 postseason.
Randy Arozarena, Tampa Bay Rays: If the Rays had managed to knock out the Dodgers, Arozarena was the clear favorite to win the World Series MVP trophy. Sidelined in July due to COVID-19 and working out at the team's alternate training site, he didn't make his Rays debut until late August. After hitting a more-than-respectable .281/.382/.641 in 23 regular-season games for the Rays, he needed only 20 games to hit another 10 homers in the postseason.
Arozarena didn't have a big breakout in the minors until 2019, so missing the 2020 season at age 25 would have been a real blow to his career outlook. By the end of the regular season, ZiPS was projecting him as a .240/.320/.451 hitter in 2021. But after the postseason he just had, that has bumped up to .259/.335/.479 and a large role in Tampa Bay's lineup.
Joc Pederson, Los Angeles Dodgers: Pederson is more of a known entity than Arozarena, a solid corner outfielder who is stretched in center and best fits on a team that has a lefty-mashing slugger on the roster who can spell Joc against tough southpaws. With Pederson entering his first year of free agency after the 2020 season and nearly traded to the Angels, ZiPS originally projected him to hit .253/.351/.536 with 29 homers. His sub-.700 OPS 2020 season trimmed that to a sub-.800 OPS expectation. His October, however, salvaged some of that, and while a projected .242/.328/.492 line for 2021 won't get him a giant contract, he ought to do better than a one-year pillow deal.
Charlie Morton, Tampa Bay Rays: Morton had a FIP in 2020 in line with his previous performances (3.45), but ERA has survived a lot better than pitcher wins in modern analytics (for good reason) and nobody wants to go into the offseason with a 4.74 ERA. At 37, this will likely be Morton's last chance to get a multiyear contract, and his postseason performances were enough to move his 2021 ERA projection from 3.51 to 3.35.
Framber Valdez, Houston Astros: Entering the 2020 season, ZiPS projected Valdez at a 4.47 ERA. His much-improved control chopped three-quarters of a run off that figure, and his four excellent starts in October were responsible for nearly a third of that improvement, putting Valdez into solid No. 2 starter territory.
Manuel Margot, Tampa Bay Rays: There has always been a whiff of disappointment around Margot, a denizen of many a top 100 prospect list from 2015 to 2017. A league-average player in his rookie season at age 22, he largely hasn't progressed since then, and arguably the reverse is true. Tampa Bay keeps its roster churning and his .269/.327/.352, one-homer line in 2020 wasn't exactly going to cement him into the team's future plans. However, 2020's postseason was just enough to squeeze him over a projected 2.0 fWAR mark with a .254/.308/.414, 2.1 WAR forecast for 2021.
Justin Turner, Los Angeles Dodgers: Until potentially becoming a COVID-19 superspreader in Game 7 and the ensuing celebration, Turner was having a solid postseason, thanks mainly to an 8-for-25 performance against some of Tampa Bay's top pitching with six extra-base hits (and two homers). While his .804 OPS in the postseason wasn't a huge needle mover by itself, it still boosts his projection by reducing any overall uncertainty, something that's quite important for a third baseman heading into free agency as he's about to turn 36. Just having a couple dozen more games is enough to improve his initial .835 OPS projection for 2021 to .850.
Julio Urias, Los Angeles Dodgers: Changes in walk rate and strikeout rate "stick" for a pitcher very quickly. So it's good news for Urias -- and the Dodgers! -- that he was so dominant in the postseason. His 1.17 ERA in 23 innings of postseason work, nearly half as many innings as his 2020 season total, wasn't a BABIP-induced mirage, as his 29-4 ratio of strikeouts to walks blew away anything he had previously done in the majors. No, he's not going to have a 1.17 full-season ERA in 2021, but ZiPS now sees him maintaining an ERA comfortably under 4.00 as a full-time starter.
Ian Anderson, Atlanta Braves: After the postseason, it almost feels as if Anderson is an ironclad No. 3 starter when Mike Soroka returns, but before 2020 his highest level of professional experience was five not-particularly-good starts for Triple-A Gwinnett in 2019. His six starts in the regular season provided a huge bump to his outlook -- Baseball Prospectus once coined TINSTAAPP or There Is No Such Thing As A Pitching Prospect -- for good reasons. Adding a productive postseason to those half-dozen turns essentially bumps Anderson's appearances at the highest level of baseball by more than 50%. If you assume 180 innings from him in 2021, ZiPS now has Anderson passing the 3.0 fWAR mark, and his reaching borderline All-Star territory wouldn't be a stretch.
Giancarlo Stanton, New York Yankees: ZiPS has never really soured on Stanton, but the reality is that his playing in only 41 regular-season games in two seasons, both years at the end of the typical prime years for a hitter, has increased the error bars for 2017's NL MVP. Every little bit of playing time helps, and squeezing in six homers in seven games this playoff season was helpful. It's not even bumping the projection from an .890 OPS to a .905 OPS that is the highlight, it's the improvement of his downside scenarios. Before the playoffs, his 10th-percentile project was an OPS of .750, and his 20th, an OPS of .784. These numbers have jumped to .783 and .822, respectively. You want lousy players to be risky; you want a lot more certainty with the good ones.