Prospectus co-founder Joe Sheehan often says that fans would be better served by baseball writers if they all put down their pens and pushed away from their keyboards from Opening Day until Memorial Day. Rany Jazayerli—another co-founder—ran a three-part study back in 2003 that provides some objective support to that subjective statement: it takes about 48 games for a team’s seasonal performance to become more predictive of their final record than a simple blend of their three previous seasons’ records, and a regression factor. After 10 games, that rough preseason projection is still more than six times as predictive of final record as actual performance is.

Joe isn’t wrong, and Rany’s math wasn’t, either. We have some tools that change the way we perceive the early segment of the season, though. For one, we have PECOTA, which was just making its maiden voyage through April when Rany wrote up his study. For another, we have the Playoff Odds Report, which uses PECOTA and a Monte Carlo simulation that repeats the season thousands of times to give us an estimate of the chances that each team will make it to the postseason.

We don’t have to make silly statements, like that the Royals have a chip on their shoulder because of the national media’s disrespect, or that the Royals learned how to win from James Shields and still carry his spirit with them like the ghost of Ben Kenobi, or that the Royals discovered the joy they feel in playing together and permanently unlocked their potential. We don’t have to project a new and different performance level for a team, based on their minute sample of performance. (The report will do that for us, in small steps, as the season goes along.) We can simply look at how a team’s early-season showing—and that of the rest of the league—has affected their chances of reaching the playoffs, and talk about why, and how much to trust that number. Sam Miller did this just last spring, and I found it to be both fun and informative. Thus, to lighten my tread on Sheehan’s commemorative paver here at BP HQ, I’ll retrace Sam’s steps, only with a new set of teams.

Last year, eight teams saw their Playoff Odds swing by six percentage points or more over the first week. This season, with a few more teams having streakier starts, there are 10 such teams, but the interesting cases are the four biggest risers, and the four biggest fallers. Let’s run them down. (Keep in mind, all of these numbers are as of the end of the action on Monday. Maybe in Week 15 I’ll stay up all night to report on up-to-the-minute Playoff Odds changes. For now, the day-old numbers serve our purposes just fine.)

Kansas City Royals: 13.3 Percent Added, from 14.1 percent to 27.4 percent
It only took the Royals a week to (nearly) double their Playoff Odds. Winning seven straight games to open the season will do that for you, especially if three of the wins come against a prospective competitor for your own division crown. It would be silly to pretend that there’s nothing sustainable here, but there’s an awful lot that is obviously unsustainable.

They’re hitting .353 on balls in play; opponents are hitting .229 on balls in play. The pitching staff has stranded 79.8 percent of the runners they’ve put on base, the fourth-highest rate in the league. They’ve committed just one error, and are tied for the highest fielding percentage in baseball. Most gallingly, they have a .202 ISO—this team that hit 95 home runs all year last season is one of the best power-hitting teams in the league so far.

They missed Chris Sale in Chicago and Garrett Richards in Los Angeles. Because of Ervin Santana’s suspension and Ricky Nolasco’s balky elbow, they got Trevor May in the first game in Minnesota. The story here is: The Royals are playing out of their minds and over their skis, making no mistakes and missing no opportunities. That all will end soon, but thanks to these banked wins, they’re a little more than a one-in-four shot to reach October.

Detroit Tigers: 11.2 Percent Added, from 53.2 percent to 64.4 percent
Through Monday, half of their wins came against the Twins, and perhaps we should only give them half credit for those. They outscored Minnesota 22-1 in three games, but have outscored the Indians and Pirates only 29-20. The Indians were (by the preseason Playoff Odds) the most credible threat to the Tigers’ claim on the division crown; sweeping them goes a long way. The White Sox’s slow start also helps Detroit, which has gone from the leader of a clustered pack to the clear favorite, 53.5-percent likely to win the division and avoid the coin-flip game. No one else has even a 20-percent chance to win the Central.

Now, the Tigers’ performance is even less sustainable than that of the Royals. They had a .388 team BABIP, which, there are some good BABIP hitters on that team, but the all-time record for team BABIP is .330, so bring them back to at least .320 in your head. Meanwhile, the pitching staff had allowed home runs on only 3.9 percent of all their opponents’ fly balls. These numbers are all coming back toward the pack, but it looks like the Tigers might have some permanent separation from the field.

Chicago Cubs: 9.2 Percent Added, from 41.4 percent to 50.6 percent
Through Monday, the Cubs had only played six games. Six! That’s nothing. They went just 4-2; this isn’t a Kansas City or Detroit situation. The change here comes from Chicago getting off the blocks much better than two of their Wild Card competitors (the 1-6 Marlins and the 4-4 Padres), and getting an early edge on the Cardinals (who, though a game back of the Cubs, still have twice Chicago’s chances to win the division).

There’s real reason for optimism here, though. Through Monday, the team had the seventh-highest walk rate and seventh-highest ISO in the league (though also the seventh-highest strikeout rate; this team will whiff all year). They had a .246 BABIP and a .358 opponents’ BABIP, but still owned a positive run differential (however narrowly). Kris Bryant is but a few days away, now, and the Cubs have only made forward progress toward contention while they wait for him.

Boston Red Sox: 7.6 Percent Added, from 62.6 percent to 70.2 percent
The Sox had scored six or more runs in five of seven contests through Monday, winning them all. The offensive juggernaut they carefully assembled over the winter seems to be coming together nicely. It doesn’t hurt that the Orioles, Blue Jays, Rays and Yankees beat each other up in other games, making the path to a Sox division title slightly clearer. Obviously, the pitching depth remains an issue, and obviously this increase is mostly wiped out if the Red Sox had found a way to lose between innings nine and 19 of Friday night’s game.

Seattle Mariners: 10.5 Percent Dropped, from 54 percent to 43.5 percent
At 3-4 through Monday, the Mariners didn’t exactly fall flat on their faces. Taijuan Walker had a really, really rough season debut, basically taking them out of one game. If that game goes differently, we’re not having this conversation, which underscores the fragility of these shifts in probability. The change comes largely from the 4-3 starts of the Blue Jays and Rays, the 4-4 A’s, and those red-hot Tigers and Royals, all combining to take a modest bite out of the Mariners’ chances to win a Wild Card game berth.

One hopes the offense won’t hit .197/.237/.372 all season. They have a .202 collective BABIP, which will certainly improve, but it’s harder to know whether their 4.7-percent walk rate is going to get any better: this is not an assemblage of guys noted for taking great at-bats. Seattle is built to win with pitching, and the egg laid by Walker in his first start betrayed that expectation. They’ve already played three one-run games around that, and have an even run differential except for that one blowout loss. They didn’t get off to a good start; their competition did. They still have time to make up what was lost, though.

Miami Marlins: 10.2 Percent Dropped, from 27.6 percent to 17.4 percent
Giancarlo Stanton’s team has a .285 slugging average, so the right kind of regression is forthcoming in at least one area. An awful lot of damage has already been done, though. Starting 1-6 hurts anyone, but especially a team whose hopes to reach the playoffs were already somewhat dim. Henderson Alvarez will miss some time, it seems. That’s reflected in this number. So are the lost services of Jeff Mathis and Don Kelly, though one presumes that didn’t hurt much.

San Francisco Giants: 8.9 Percent Dropped, from 39.9 percent to 31 percent
This team was 3-5 through Monday, and all of their games were against NL West opponents. That’s about what this boils down to: losing games to division rivals eats away at playoff odds in a way losses to other teams don’t. Everyone nudges a little closer to shocking the world and winning the division, and every inch they gain comes out of your probability.

The Giants are fascinating. They were practically neck-and-neck-and-neck-and-neck with the Cubs, Mets and Padres in terms of total Playoff Odds at the start of the season; they’re now a measurable distance behind all three, and way behind the Cubs. That’s not true if you isolate the odds of winning the Wild Card, but then, that’s kind of the point: The Dodgers outclass everyone in the NL West, including the Giants, so that Wild Card slot is sort of their only good chance. And it’s fading. Already.

Cleveland Indians: 8.5 Percent Dropped, from 33.1 percent to 24.6 percent
A lot of analysts (not the guys at Sports Illustrated, unfortunately, but a lot of people) will have stories for you sometime later this year, about when they realized that the Indians were a false promise. They were such a cool story in 2013, and an impressive, pesky, pitching-nerd-friendly bunch in 2014. They had some charm to them, a certain appeal, just enough to draw you into picking them. A lot of people did. I almost did, too.

What swayed me—aside from the documented volatility of their rotation, which is deep but wildly unpredictable—was the epiphany I had while perusing their offensive core last month: They could really struggle to score runs. It’s not guaranteed. In fact, they still have a shot at an above-average offense. They have some serious downside, though, and not much chance of really breaking out, the way that 2013 team did down the stretch.

It was a little of each problem that set the team back in their first week. They had a collective OBP of .296, but still scored 22 runs in six games, a respectable figure in this era. They held the Astros to three runs in three games, but then surrendered 25 in three against the Tigers. Most of their lost probability comes from the Tigers and Royals sprinting out of the gate the way they did. Cleveland will have chances to get these games back, and nothing in their performance has led me to conclude that panic is appropriate. It’s appropriate—it might even be the universe speaking to us through numbers, though it probably isn’t—that the Indians, Tigers and White Sox were the three teams contending for the AL Central at the start of the season, and that, with the Royals starting this way, the Indians’ Playoff Odds have sagged from one shot in three to one in four.

Thank you for reading

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Very enjoyable article. Thanks!
all strikes me as pointless speculation. You should take Sheehan's advice.
i respectfully disagree
I disrespectfully disagree
What's the point of analysis at all if you're not constantly revisiting assumptions and hypotheses?
Good stuff! Loved looking at Sam's article from last April.

Probably pointless right now, but I find interest in how these numbers change throughout the year...might as well start it now.

Sorry if you addressed this and I just missed it, but how much of the change in odds is attributable to changes in expected performance going forward and how much from the banked wins/losses? Is it all from the latter?

Also, a few more references, and Ben Kenobi will need his own Player Card. I imagine him as a Mickey Cochrane type (good numbers, great reputation, but perhaps a little over-rated during his time) with a beard.
I can answer that it's primarily the latter. The Royals' expected winning percentage, for example, has gone up only .003 (from .468 to .471) since Opening Day. Same with the Tigers (.514 to .517).
The most significant changes in forward-facing performance come from injuries, especially in the cases of Henderson Alvarez and Yan Gomes. The rest is, as Sam notes, mostly about what's already happened.
I recall 1984 when the Tigers started the season 35-5. (Ain't gonna happen again.) By that point, they had banked enough wins to safely play .500 ball the rest of the way to get to the playoffs (.500 would have left them with 96 wins). They did a little better than that, but not much! They didn't need to. Then they swept through the playoffs and WS.

To take this totally out of context, a strong start in my line of work (academia) can get you to the regular roster (tenure), but you have to continue to play well to be rewarded with future promotions and salary increases. I saw plenty of faculty who essentially fell over the tenure line and spent the rest of their mediocre careers as an associate professor. Fortunately, baseball expects more, but has its own form of tenure for players who are above replacement and injury free.

Back to the original point: a strong start helps a lot, but 9 games (or 6 years to tenure) doesn't make a season (or a career).
I would think that losing Jeff Mathis would tend to increase a team's playoff chances...