Opening weekend around the league saw four teams win their first three games. Three of these teams weren't big surprises: Phillies, Rangers, and Reds. The fourth was a bit more of a surprise--the Baltimore Orioles.
The O's swept the Tampa Bay Rays, doing so in style by posting 12 runs scored and only 3 against.
*Now, it's a long season, but that doesn't mean we can't have fun with Baseball-Reference's Play Index and speculate on which fans should be panicking after only 2% of the season has been played.
If we look at all teams since 1900 that have won their first three games, 44 out of 166 went on to win a pennant (28%), 76 finished in first or second place (48%). 14 of those teams went on to win the World Series (9%). Overall, these teams sported a winning percentage of 52%.
Those teams that started 0-3? Little rougher of a story.
Of the 163 teams that started 0-3, only 6 went on to win a pennant (4%) and 29 finished in first or second place (18%). These teams managed to win 50% of their games on average. The good news? Three these teams went on to win championships: the 1973 Oakland Athletics, the 1914 Boston Braves, and the 1998 New York Yankees (hat tip to Dan McCloskey for pointing out the 1998 Yankee team).
While I can't imagine a scenario where the Red Sox miss the playoffs and the Orioles make it, the numbers here have to make O's fans even happier than I'm sure they already are. And given recent history, they are entitled to it.
(Let me know if I've missed any cases. I have a feeling the B-R data may have lopped off a few.)