This morning, we looked at the regression of the Arizona Diamondbacks offense and how it’s caused the team to struggle since the end of April. But the hitters aren’t the only ones who haven’t held up their end of the bargain, so now, let’s take a look at the pitchers.
In April, the D’backs did a better job of preventing runs than any other team in baseball, posting a 3.25 ERA in their first 252 innings of work. They did it by excelling in all three of the true outcomes categories, ranking third in the NL in strikeouts (206), fourth in walks (92), and tied for first in home runs allowed (19). Brandon Webb took his awesomeness up a level, giving up just nine earned runs in 41 innings of work, while offseason acquisition Dan Haren chipped in with 37 1/3 innings of work and a 3.13 ERA himself. But, really, the stars of April were the bullpen, as the Arizona relievers (led by Chad Qualls, Brandon Lyon, Brandon Medders, and Juan Cruz) posted a 2.48 ERA as a group.
When you’re not putting people on base or letting them hit the ball over the wall, and you’re missing bats regularly, opposing offenses aren’t going to score many runs – best in the N.L. in April. Even if you got Webb and Haren out of the game, it wasn’t getting any easier. It’s tough for any bullpen to sustain pitching of that quality, however, and sure enough, the Arizona relievers have taken a pretty big step back since. In May, they posted a 4.48 ERA as a group, thanks largely to increases in their walk rate (3.41 BB/9 in April, 4.21 BB/9 in May) and in their home run rate (.49 HR/9 in April, .71 HR/9 in May). Without a bullpen slamming the door, it became harder for Arizona to hang on for close wins, and the struggles of their relievers turned games they were winning in April into losses in May.
It’s not just the relievers, however, who have taken a step back. Micah Owings was brilliant in his first four starts of the season, posting a 2.42 ERA with a 6/23 BB/K in 26 innings of work. In his last nine starts, however, he’s put up a 5.90 ERA in 50 innings of work. After winning the first four starts he made, the D’Backs are just 3-6 in his last nine, thanks in large part to the runs he’s allowed. However, D’Backs fans should be encouraged that his underlying performance hasn’t changed that dramatically. Here are his April/May core stats side by side:
April: 2.08 BB/9, 7.96 K/9, 1.03 HR/9
May: 3.22 BB/9, 7.69 K/9, 1.25 HR/9
The extra walk per game explains some of the difference, but that May profile is still quite a bit better than his ERA would suggest. Owings will bounce back, and I wouldn’t worry about him much if I was an Arizona fan.
While the pitching staff hasn’t been as good as they were in April, there are fewer reasons for concern here than with the offense. Webb/Haren/Johnson/Owings/Davis is a terrific rotation, and the bullpen is still solid, even if not best-in-the-league as they were early on in the year. The D’Backs are going to be among the league leaders in preventing runs, and even with the rough patch they’ve gone through, they should be happy with the personnel they have. They just need another hitter.