Castillo gave Chicago (70-88) a 2-0 lead by delivering a two-run shot during the bottom of the second inning off Cardinals starter Shelby Miller. The Cubs forced Miller out of the game after just 4 1/3 innings of work after he allowed another home run – this time to rookie Matt Szczur in the fifth.
Miller was pulled after walking Javier Baez, moving starter Kyle Hendricks up to second. Hendricks (7-2, 2.45 ERA) made it just an inning longer (5 1/3) than his counter part in his second-to-last outing of the year, finishing with one walk, four strikeouts, and three earned runs off five hits including a home run.
The lone Cardinals home run came off the bat of outfielder Matt Holliday, who tied the game up at 3-3 with a two-run blast of his own.
Jorge Soler put himself in scoring position during the bottom of the eighth inning, doubling on a sharp line drive to right field. It was the rookie outfielder’s seventh double of the year, but nothing would fail to capitalize as Castillo struck out swinging and Chris Coghlan grounded out to retire the side.
St. Louis (88-70) would be unable to score a go-ahead run as Zac Rosscup replaced Hector Rondon on the mound. Rosscup (1-0, 9.45 ERA) struck out Matt Carpenter, and was able to get Jon Jay to fly out to Coghlan before striking out Holliday.
First baseman Anthony Rizzo doubled to center field shortly after Javier Baez was called out on strikes to start things off in the tenth, once again giving the Cubs the opportunity to make something happen with runners in scoring position.
Soler would ground out to first baseman Matt Adams, pushing Rizzo over to third base. Luis Valbuena would make his way to the plate 0-for-2 with two walks on the night, and would pick up number three after being intentionally walked by Cardinals reliever Pat Neshek.
This set up Castillo with an opportunity to win the game with runners on the corners and one out in the inning. Valbuena would advance to second with the Chicago catcher at the plate on defensive indifference, giving his team a better shot at picking up win number 70.
Castillo would miss on a 80 mph slider delivered by Neshek, but then connected on the very same pitch, driving it to center field to plate Rizzo to give his team a walk-off victory. The Cubs’ backstop finished the ballgame 2-for-5 with three RBIs, two strikeouts with two left on base. Both Javier Baez and Arismendy Alcantara combined to go 0-for-9 with one walk, and seven strikeouts.
Wednesday night, the Cubs will send Jake Arrieta (9-5, 2.65 ERA) to the mound to take on John Lackey (3-2, 4.50 ERA) during the final home game of the 2014 campaign with the first pitch scheduled for 7:05 p.m. CT, which will also be the last home game broadcast on WGN AM 720.
Chicago can help keep the Pirates in the hunt for the NL Central crown by taking the series away from St. Louis.