The Dodgers, Mets, Cardinals and Cubs are playing in the National League Division Series for a chance to play for the NL pennant.

Here's a primer:

* The Dodgers last won the World Series when they beat Oakland in 1988 after winning the National League Championship Series against the Mets. The Dodgers won in seven games with Orel Hershiser the pitching star. He threw eight innings in Game 1, six in Game 3, recorded a save in Game 4 and pitched a 6-0 shutout in Game 7. Ironically, Mets manager Davey Johnson commented before Game 7 that the Dodgers might be wearing out Hershiser.

* The weirdest play in Dodgers-Mets history happened in a postseason game in 2006 when Mets catcher Paul Lo Duca tagged two runners at the plate on the same play. Here's what happened: L.A.'s Jeff Kent and J.D. Drew hit singles against John Maine. Russell Martin hit a ball off the wall in center. Kent tagged up, Drew went halfway. But, then they both took off when the ball fell. The relay throw went from Shawn Green to Jose Valentin to Lo Duca, who couldn't believe his eyes when he saw two runners trying to score. He tagged them both out.

* Is the Cardinals-Cubs the best rivalry in baseball? That's open for debate because there is also Red Sox-Yankees and Dodgers-Giants. The Cardinals and Cubs have played more than 2,300 games and this is the first time they've met in the postseason. Since 1996, the Cardinals have made the postseason seven times, the Cubs four times. But each time the Cubs made it - 1998, 2003, 2007 and 2008 - the Cardinals didn't make it. The Cubs have 1,197 wins in the all-time series, 50 more than the Cardinals. There are also a few ties.

* While the Cardinals and Cubs have never met in the postseason, there are some interesting historic notes between the two teams. Cardinals Hall of Famer Stan Musial got his 3,000th career hit in Wrigley Field while the Cardinals' Mark McGwire hit his 62nd home run in St. Louis while playing the Cubs. Also, Hall of Famer Rogers Hornsby won the 1925 NL MVP for the Cardinals and was the 1929 NL MVP for the Cubs.

* Starlin Castro, 25, the one-time face of the Cubs franchise, has manager Joe Maddon to thank for his career turnaround this season. Castro was the shortstop, but was benched when he didn't hit. Eventually, Maddon worked him into the lineup as a utility player, finding roles where he could have success. It worked: Castro went from hitting .247 in the first half to .295 in the second, including .376 since Aug. 30.

* Dodgers lefty Clayton Kershaw and right-hander Zack Greinke have piled up the Cy Young hardware, but have struggled to help the Dodgers win a World Series. In 10 combined postseason starts over the last two seasons, Kershaw and Greinke have combined to go 2-5 with a 3.53 ERA. Kershaw has won three NL Cy Young Awards and Greinke, who has won the award in the AL, is one of the favorites to win the award this year with a 1.66 ERA. Greinke was the NL ERA champ this season, stopping Kershaw's streak of four consecutives of winning that title. Kershaw had a 2.13 ERA.

* The Dodgers acquired Jimmy Rollins from the Phillies to play shortstop and take advantage of his postseason experience, but when rookie Corey Seager got a chance to make an impression during his September call-up, he made the most of it. Seager, 21, brother to Seattle third baseman Kyle Seager, hit .337 in 21 games. Seager could end up replacing Rollins at shortstop during the postseason.

* Mets outfielder Curtis Granderson, 36, is trying to get back to the World Series for the first time since 2006, when he played for the Tigers, who lost to the Cardinals in the World Series. He hit .294 with two home runs and five RBIs in the Tigers' American League Division Series win against the Yankees and hit .269 when Detroit beat Oakland for the AL pennant. But his average dipped to .095 in the World Series against St. Louis. Granderson played in the postseason for the Yankees in 2010, 2011 and 2012.

* The Mets' big story is pitcher Matt Harvey, who is coming back from Tommy John surgery, and how many innings he will be allowed to pitch. We don't know how far the Mets will go with him if they advance. Harvey will start Game 3 versus the Dodgers at home in Citi Field, and even though he's over his 180-inning limit for the season, the question is how many innings will pitch. For sure, manager Terry Collins isn't going to take him out of the game if he has a shutout after five innings, as he did Sept. 20 when Harvey was pitching against the Yankees.

* At 33, Cardinals catcher Yadier Molina is trying to find a way to play in this postseason after having a ligament injury in his left thumb. His Cardinals teammates call him the leader and the guy who keeps the calm. Molina played with bad knees in the 2011 postseason; last year, he played with a ligament injury in his right hand. Molina has played in 86 postseason games, which ranks 10th all-time.

* The Cardinals' No. 1 pitcher, Adam Wainwright, 34, is back, even though when he went out with an Achilles injury on April 25, the Cardinals weren't sure they were going to see him again. But, he returned to pitch three innings of relief in the final week of the season, and Cardinals manager Mike Matheny says that while Wainwright won't start, he could be a two- or three-inning guy out of the bullpen. Wainwright has made 12 postseason starts for the Cardinals. In 2006, he was their closer, picking up four saves.

* The Mets were one of the worst run-producing teams in the NL during the first half, but that all changed in the second after acquiring Kelly Johnson, Juan Uribe and Yoenis Cespedes in July trades. Cespedes was the biggest factor in the Mets' turnaround, hitting .287-17-44 as the Mets led the NL with 373 runs in the second half.

* The Cardinals' 3.22 ERA was the best in the NL in the second half and it was led by John Lackey's 2.50 mark. Lackey has won World Series titles with the Angels in 2002 and Red Sox in 2013. He'll be pitching against the Cubs lefty Jon Lester, who was a teammate of Lackey's when the Red Sox won the World Series against the Cardinals in 2013.

* The Cubs' Jake Arrieta had a 0.75 ERA during the second half and then dominated Pittsburgh in the wild card game, but what about the rest of Chicago's rotation? Lester has been strong, setting the Cubs' single-season strikeout record for a lefty (207), breaking the record of 202 by Ken Holtzman in 1970. But the rest of Chicago's rotation is average at best when you include Kyle Hendricks (4.44 ERA in the second half), former Oriole Jason Hammel (5.10) and Dan Haren (4.01).