A few weeks ago, I decided I wanted to put together weekly recaps of the most important plays, the most and least valuable Cubs, and the best and worst managerial decision of each week of the season. These recaps will likely change in structure over the course of the season, so please feel free to let me know what you like or don't like about the current structure as well as what you would like to see in future recaps.
The main criteria for a lot of these categories is Win Probability Added (WPA). I like WPA because it does a good job highlighting the biggest moments of a game, as well as the players who most contributed to a win or a loss. WPA is the difference in win expectancy between the start of a play and the end of a play. This difference is then credited to the batter and the pitcher involved in the play. In other words, WPA essentially measures how individual players affect their team's win expectancy on a per-play basis.
As an example, let's look at the first play of the Cubs 2012 season: The win expectancy for the Cubs started out at 50%. When Ian Desmond singled off Ryan Dempster in the first at-bat of the game, the Cubs win expectancy declined to 46.4%. The difference, or WPA, was 3.4%, or .034 wins. Desmond was credited +.034 wins and Dempster was credited with -.034 wins.
If any of that doesn't make sense, please let me know and I'll do my best to clear up any confusion. Without further ado, here's the recap for the first week of the season.
The Three Most Important Plays
4/7 Top 8, bases loaded with 2 outs: Chad Tracy singles on a ground ball to right field off of Carlos Marmol scoring the tying and go-ahead runs, resulting in a .-456 WPA. The Cubs had a 69.9% chance of winning the game prior to the at bat, and a 24.3% chance of winning the game after the at bat.
4/5 Top 9, man at 2nd base with 2 outs: Ian Desmond singles on a line drive to right field off of Carlos Marmol to bring in the go-ahead run, resulting in a -.357 WPA. The Cubs had a 53.1% chance of winning the game prior to his at bat, and a 17.4% chance of winning the game after his at bat.
4/5 Bot 9, man at 3rd base with 1 out: Jeff Baker's is out on a fielder's choice grounder to third base resulting in a -.311 WPA. In other words, we had a 40.5% chance of winning the game prior to his at bat, and a 9.3% chance of winning the game after his at bat.
Most Valuable Cubs
Ryan Dempster: .509 WPA. 7.2 innings of 1-run baseball.
Jeff Samardzija: .386 WPA. 8.2 innings of 1-run baseball.
Ian Stewart: .332 WPA. Represented the tying run with a one-out triple in the bottom of the 9th on Thursday.
Least Valuable Cub
Carlos Marmol: -.911 WPA. Marmol essentially blew games 1 and 2 of the season. While Wood was also at fault, his WPA was not nearly as bad as Marmol's since Marmol gave up the go ahead runs in both games.
(The WPA for most and least valuable Cubs is the cumulative WPA over the course of the week.)
Best Managerial Decision
Pulling Dempster out of the game after he struck out Danny Espinosa for the second out of the 7th inning. Though Dempster had pitched four consecutive 1-2-3 innings prior to the 8th, and had just come off of striking out Espinosa, he was sitting at 108 pitches and had already allowed a couple of long fly balls to the upcoming hitter, Ryan Zimmerman.
Worst Managerial Decision
The contact play in the 9th inning of Thursday's game. The ball could have been hit (i) right at an infielder, (ii) a few feet to an infielder's left or right, or (iii) through a hole in the infield. Zimmerman had so much time to throw home that he would have been able to gun down Mather even if he had to move a step or two to his left or right. Thus, even with the contact play on, Mather likely only scores if the ball gets through a hole. If the ball gets through a hole, Mather would score even if the contact play wasn't on. Thus, the contact play doesn't really add any strategic value - especially when the team is down by a run in the 9th.