We're only 31 games into the season, but I was curious for some unkown reason who had the best game of any player on the team. Win Probability Added (WPA) is the perfect stat for this. Below are the top 10 WPA's of the season for the Cubs.
10. Matt Garza, April 29th @ Phillies: The Cubs won 5-1 behind Garza's 7 inning, 1 hit performance. He also walked only 1 and struckout 10. This is the only time Garza is in the top 10, but this start wasn't even his best one of the season if we use Game Score. He has the top 2 game scores of the season for Cubs pitchers with an 84 in this one and an 85 on April 12th. WPA: .353
7. Jeff Samardzija, April 8th vs Nationals: The Cubs beat Jordan Zimmerman and the Nationals 4-3. Samardzija nearly completed this game as he threw 8.2 innings, allowed 4 hits, 3 runs (only 1 earned), walked no one and struckout 8. WPA: .380
6. Ryan Dempster, May 3rd @ Reds: The 2nd night in the row the Cubs got a brilliant performance by a pitcher, but this time they lost. Dempster went 8 innings, didn't allow a run and allowed only 3 hits. He walked 1 and struckout 6. The Cubs led 3-0 entering the 9th and Carlos Marmol allowed 3 runs without recording an out. WPA: .380
5. Paul Maholm, May 9th vs Braves: Maholm has an ERA just over 4 and 4 wins on the season while Dempster has no wins and a league leading 1.02 ERA. Anyway, in this game Maholm was excellent as the Cubs beat the Braves 1-0. You remember this since it was the last game they played. He threw 7 innings, allowed 3 hits, no runs, 3 walks and struckout 3. WPA: .428
3. Bryan LaHair, April 24th vs Cardinals: This is the 3rd time this game has appeared in the top 10. LaHair was 2-4 with a walk and hit the game tying home run in the 9th inning. Since we know so many players have performed well in this game it's worth noting that this game also probably has some of the worst performances. WPA: .450
2. Ryan Dempster, April 5th vs Nationals: Dempster threw as well as you could hope on Opening Day as he threw 7 innings, allowed 5 hits and a run. He walked 1 and struckout 5. The Cubs took a 1-0 lead into the 8th and Dempster was relieved by Kerry Wood who blew the first of several blown saves for the Cubs this season. Carlos Marmol allowed a run in the 9th and the Cubs lost 2-1. This is the only game in the top 10 the Cubs lost. WPA: .505April 23rd vs Cardinals: Mather went 2-3 with a walk in this game, but the Cubs trailed 2-1 entering the bottom half of the 9th. After Jason Motte struckout Soriano, he walked LaHair and Geovany Soto. Clevenger pinch hit for Rafael Dolis and advanced the two baserunners on a groundout. With 2 outs, trailing by 1 and runners on 2nd and 3rd the Cubs had just a 23% chance of winning. Then Joe Mather singled to CF scoring both runs to give the Cubs the win. WPA: .756
As you can see, no performance compares to Mather's game-winning hit against the Cardinals. I was somewhat surprised to see that among the top 10 there were 7 pitchers. Then again, the Cubs offense has sucked and they've been all about starting pitching this season so it shouldn't have shocked me.
The worst 3 in WPA all belong to Carlos Marmol. In those 3 outings Marmol threw a combined 0.1 innings, allowed 4 hits and walked 6. 6 runs crossed the plate though only 4 were earned. He's lucky to not have given up more runs than he did. His WPA was -0.698 on May 3rd against the Reds, -0.640 on April 7th against the Nationals and -0.530 on April 24th (there's that game again) against the Cardinals. The 4th worst was Samardzija's start against the Marlins on April 19th (-0.431). Chris Volstad had the 5th worst performance on the team the very next day against the Reds (-0.397).