I started with the National League (here, here, and here). Already hit the AL West, so now it's the Central.
Detroit Tigers, 93-69: Want to know why the Tigers were so eager to sign 39-year-old former Rangers closer Joe Nathan to a free agent contract back in December? No team in baseball had a larger differential between ERAs for starters (3.44) and relievers (4.01). For most teams, the bullpen had a lower ERA than the starters. Nathan has a career ERA of 2.14 since joining the AL in 2003.
One more Tigers fun fact: In limited opportunities (i.e., interleague play), Tigers pitchers had a .222/.300/.278 slash line, equal to a .578 OPS. A .578 OPS is better than White Sox catchers, Blue Jays second basemen, and Royals shortstops last year.
Cleveland Indians, 92-70: Cleveland feasted on lefties, going 36-20 against them. Their .643 winning percentage against southpaws was the best in the league. They had problems against righties, compiling just a .528 winning percentage. The .115 differential was the most in the league. It's unusual for a team to do better against lefties than righties (only four AL teams did), and Cleveland was helped by three switch hitters in the lineup. They team was also helped by playing in the same division as the White Sox, against whom the Indians had a 17-2 record, the best head-to-head record in baseball.
Minnesota Twins, 66-96: OK, I'm calling this series Things I Didn't Know, but I did know this one, as I discussed it in December: Twins relievers had more strikeouts last year than Twins starters. I'm repeating it because it's so crazy. It's never happened before, and as I said, it's not because the Twins relievers are all flamethrowers: their strikeouts per nine innings ranked 23rd among the 30 major league bullpen. It's a reflection about how amazingly bad the Twins starters (their 5.26 ERA was the worst in the majors by almost half a run) were.
Chicago White Sox, 63-99: When you play in a hitter's park, you wind up with inflated hitting statistics. US Cellular Field is a hitter's park. Yet the White Sox scored only 598 runs last year, the fewest in the American League, and the fewest for the franchise since 1980. Of the players ending the year on Chicago's roster, only first baseman Paul Konerko, DH Adam Dunn, utility infielder Jeff Keppinger, and middle reliever Matt Lindstrom were even born the last time the Sox had fewer than 600 runs scored.