The success of the San Francisco Giants over the past four seasons has been largely predicated on their excellent pitching and defense, aided by the friendly confines of AT&T Park. The Giants have allowed the fewest runs in the game since the 2009 season began.
However, with Brian Wilson down for the count this season and Tim Lincecum struggling mightily in the first half, the Giants are not quite as statistically dominant in the run prevention category so far in 2012. Lincecum has turned it around in the second half, but now Ryan Vogelsong and Madison Bumgarner are slumping on the mound.
The Giants team ERA is 3.75, eighth best in the league. However, since the All-Star break the staff ERA is 3.93, which is only 13th overall. Thus far in September, it's down to 4.50, which is 21st.
Over his last six starts, Ryan Vogelsong has thrown 26.1 innings, allowed 43 hits, 28 runs and six home runs for a 9.57 ERA. While his strikeout rate (10.94 K/9) and walk rate (2.39 BB/9) are outstanding over that time, in between the whiffs, he's getting absolutely pounded.
Over Bumgarner's last four starts, he's thrown 21 innings, allowed 31 hits and 18 runs for a 7.29 ERA.
In both cases, fatigue, command and bad luck or bad defense on balls in play appear to be the main culprits.
In a start against San Diego on August 19th, Vogelsong allowed 30 foul balls on 96 pitches, which suggested that he isn't getting the same finish on his pitches. While the radar gun readings are the same as they were when he was preventing hits and runs, the reaction of the hitters appears to have changed a bit. Fatigue may also be a factor in his inability to consistently pound his intended target.
One thing Vogelsong might want to consider is minimizing the use of his cut fastball. According to FanGraphs, that pitch has been worth -2.7 runs for Vogelsong this season, compared with his fastball (+7.7), curve (+2.0) and change (+0.4).
Bumgarner's issues were on display on Tuesday night in Colorado. He could not consistently keep the ball down in the zone, which led to a lot of hard contact from the Rockies. Bumgarner's fastball velocity was up to 94 MPH in the first inning, but he could not maintain that velocity, and by the middle innings he was topping out at 91.
The location mistakes and inability to maintain velocity throughout the start are likely signs of wearing down, which isn't surprising given that he's only 23 years old. He's also throwing his slider about 40 percent of the time, which can be a tough pitch on the elbow when used at such a high rate.
Bumgarner's low arm slot prevents him from throwing a two-seam fastball (Pitch F/X classifies some of his pitches as two-seam fastballs, but pitching coach Dave Righetti told Tim McCarver that Bumgarner only throws a four-seam fastball due to his arm slot during a recent broadcast on Fox Saturday Baseball).
The low arm slot also prevents him from snapping a consistently good curveball. He throws his fastball and slider 82 percent of the time, and while they are both excellent pitches, they also both have hard movement to his glove side (in to a right-handed batter).
His low arm slot prevents him from getting movement to his arm side (away from a righty), except when he uses the change-up. However, the change-up, like the curve, has been an inconsistent and under-utilized pitch for him.
Hitters can basically focus on one speed (hard) and one type of movement (to the glove side) from Bumgarner. If he has good command, they still have no chance, but on the days when he isn't fine with his location, he becomes very hittable.
In the end, Bumgarner and Vogelsong were both so good last year and through most of this season that their recent struggles are likely just a blip on the radar. They both look a little fatigued and less crisp with their stuff and command. They also have gotten little help from the defense in turning balls in play into outs over the past few weeks, which helps explain those high hit totals allowed.
Perhaps an extra few days of rest between starts down the stretch will do the trick to get both starters back on track for October. With a six game lead in the division and only 20 games left, extra rest is a luxury the Giants may soon be able to afford.