Last year, the Patriot-News of Harrisburg, PA issued a correction for a piece it had written on the Gettysburg Address, 150 years earlier. “We pass over the silly remarks of the President,” they had written in 1863. “For the credit of the nation we are willing that the veil of oblivion shall be dropped over them and that they shall be no more repeated or thought of." It took some time, yes, but Patriot-News staff eventually did check themselves before they wrecked themselves.

That’s the sort of correction I’m expecting from the Boston Globe some decades from now, when they realize how absurd the closing line of Dan Shaughnessy’s column was last week: “Wednesday night… just became a Must Win” for the Red Sox. There are no must wins on Day 2 of a baseball season, and certainly no Must Wins. Shaughnessy, on the other hand, hopefully appreciates that his next column just became a Must Not Suck.

That said, games do count, and they do add up, especially with teams' schedules so frontloaded with intra-division matchups. So while 22 teams’ playoff odds are virtually unchanged in the past seven days—a swing of no more than six percentage points in either direction—a few clubs have already seen (relatively) substantial shifts in their seasons. These be they:

San Francisco Giants: 12.9 percent added
From/To: 49.5 to 62.4 percent
What happened: Led the league in home runs (and second in doubles) in the first week, scoring seven runs or more in four of seven games. (Last year’s team scored seven or more in 17 percent of its games.) Pitching staff struck out 57, walked 12 in 61 innings. Clayton Kershaw scratched from anticipated start against them. Club has hit .251/.315/.449 overall (quite good!) but .370/.426/.593 with runners on (probably not sustainable!).
Also: Vagabond infielder Brandon Hicks, in 10 plate appearances, has lifted his career OPS by 92 points this year. His WPA is higher than Alex Rios’ was last year.

Detroit Tigers: 10.4 percent added
From/To: 58.8 to 69.2 percent
What happened: Back-to-back walkoffs against division rival, and 3-0 in one-run games. Easy enough to imagine both those walkoffs going the other way and Detroit being on the other side of this list. Still, six of nine regulars have an OPS better than .925, and the team’s .288/.337/.488 is the best in AL by a healthy margin. Their starters’ ERA is second-best in American League, just behind Oakland.
Also: By Defensive Runs Saved, Tigers are already last in defense. (FRAA has them solidly below average.) Defensive metrics are incredibly unreliable in such samples, but give ‘em their due credit here.

San Diego Padres: 8.1 percent dropped
From/To: 29.3 to 21.2 percent
What happened: Padres have trailed in 40 innings this year; they’ve led in just four. Lost two of three at home to division favorite Dodgers, then two of three to league underclass Marlins; meanwhile, the Giants’ increased odds have to come from some team’s column. No. 3 hitter batting .130/.167/.130; cleanup hitters batting .095/.208/.095; no. 5 hitters: .095/.125/.182. Club hitting .195/.246/.271 with runners in scoring position, scarcely better overall.
Also: Josh Johnson hurt (!).

Arizona Diamondbacks: 8.0 percent dropped
From/To: 17.3 to 9.3 percent
What happened: Worst pitching in NL so far by ERA, FIP, or xFIP. Hitting .296/.371/.408 in low leverage, .218/.228/.364 in high; opponents hitting .273/.365/.474 in low leverage, .388/.411/.714 in high. Starters’ ERA is 6.18, relievers’ is 6.11.
Also: Lead all of baseball with 13 infield hits, nearly twice as many as next NL team.

Seattle Mariners: 7.6 percent added
From/To: 30.3 to 37.9 percent
What happened: Swept PECOTA’s preseason AL West favorite, the Angels, on the road, outscoring them 26-8; no AL West team over .500. So the Mariners are in first place by two games instead of the more expected game-or-two deficit. Even without their no. 2 and 3 starters, the Mariners’ first five starts all ranked in baseball’s top 60 (90th percentile) by Game Score. Young(ish) question marks Dustin Ackley and Justin Smoak each had big weeks, and six of nine regulars (but not Cano) homered.
Also: Roenis Elias made his first start ever above Double-A, walked as many as he struck out, got six swinging strikes and mostly fly balls, but allowed one run.

Atlanta Braves: 6.9 percent added
From/To: 36.6 to 43.5 percent
What happened: Haven’t allowed more than two runs in a game yet, including back-to-back wins on the road against division favorite Nationals. With runners on, have held batters to .150/.212/.233 line and have baseball’s best strand rate at 90 percent. Hence, lowest ERA in the game despite seventh-best FIP, 13th-best xFIP. Still, just getting through the rotation a couple times before the imminent returns of Mike Minor, Ervin Santana, and Gavin Floyd counts as a big achievement, and the Braves will certainly bank a bit of good luck early in the season.
Also: Uptons: .149/.200/.170, 42 percent strikeout rate.

Los Angeles Dodgers: 6.6 percent dropped
From/To: 94.0 to 87.4 percent
What happened: Two losses at home to the Giants. Only the AL East and AL West currently have a tighter margin between projected first- and second-place teams than the NL West, so these games are obviously important (Must Wins?). Still overwhelming favorites, with baseball’s highest playoff odds, division odds (60 percent), and World Series odds (13 percent).
Also: Chone Figgins is tied for the highest walk rate in baseball.

Los Angeles Angels: 6.5 percent dropped
From/To: 62.5 to 56.0 percent
What happened: Swept by Mariners at home before taking two of three from Houston. Third-best hitter has .261/.320/.348 line, though maybe nine of the club’s 58 innings have come against above-average pitchers. Three full-timers, including Albert Pujols, still in contention for this year’s DiSars. Six of seven relievers have allowed a run, and five have allowed multiple.
Also: Triple-A club hitting .342/.414/.577. Triple-A club has 6.50 ERA.

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Are these playoff percentage changes based simply on win-loss records so far this year? Or do they incorporate playing time changes based on injuries (and the resultant decreased playing time) incurred in the first week?
With all due respect, please don't quote Dan Shaughnessy. It only encourages him.

Thank you.
Interesting article, Sam. I imagine the volatility will diminish as the season progresses. Is that right? Or is an unexpected win worth just as much late in the year?
I think it's the opposite. The later in the season, the closer to a conclusion, the more a win is "worth," though of course that's mostly an optical illusion.
Actually, I think as the season goes on, the "average" win is worth exactly the same amount as it was at the beginning. For teams that are on the cusp, that win is worth much more at game 155 than it was at game 1. For teams out of contention, or a lock to make postseason, it's obviously not worth anything.
I don't see how the average would stay exactly the same over the season, but something like this is clearly the case. As with base-out situations within a game, there are higher and lower leverage situations, and late in the game/season, you are more likely to have very high or very low leverage. Most teams have a 0% swing in playoff odds riding on their 162nd game of the season, but occasionally a few teams have a 100% swing on the line.