For the third year in a row, the Pittsburgh Pirates played well during the first half of the season. Yet entering the second half, the offense sits below average for a National League squad with Pittsburgh hitters generating less than four runs a game. But the pitchers have posted the best ERA in the majors at 3.07.
Can the Pirates expect that level of pitching to continue? If the offense doesn't improve, they will need to keep runs off the board to prevent a second-half collapse, which has occurred in each of the last two seasons.
The Pirates' ERA gives pause. Pitchers control three aspects of the game independent of their fielders. Strikeouts, walks and home runs allowed form the basis of a statistic known as Fielding Independent Pitching (FIP). The figure estimates the ERA of a pitcher or a staff based on those three outcomes and assumed average defense.
The difference between ERA and FIP gives an idea of the defensive support (or lack of it) behind a pitcher or staff. The St.Louis Cardinals (57-36), who lead the Pirates (56-37) by one game in the NL Central, own the best FIP in the NL:
2013 pitchers / Cardinals / Pirates
Strikeouts per 9 IP / 7.8 / 7.6
Walks per 9 IP / 2.5 / 3.2
Home runs per 9 IP / 0.68 / 0.75
FIP / 3.28 / 3.68
ERA / 3.39 / 3.07
The Pirates FIP difference of 0.61 runs represents the largest gap in either direction in the NL. The Pirates' ability to turn batted balls into outs accounts for the anomaly. Batting average on balls in play (BABIP) looks at non-home run balls in play. The lower the number, the better the pitching and defense. The NL median team stands at .294, with the Colorado Rockies at the upper end with a .306 BABIP and the Cincinnati Reds near the lower end at .276. Pittsburgh sits well below them at .265. The Pirates' BABIP is not just good, it's an extreme outlier.The Cardinals pitch better in all three of these categories, especially walks. That trend should lead to better results for St.Louis, all things being equal. But that's not the case.
A number of factors could contribute to a low BABIP. The defense could exhibit excellent range, getting to balls others see pass by for hits, or the coaching and scouting of position players based on batter tendencies and the way the pitchers work the hitters could be exceptional.
The pitchers contribute as well, as those who avoid solid contact should produce batted balls more easily fielded. Finally, there is luck. Line drives find gloves, long flies get knocked down by the wind, the bad umpire call goes your way. How do these factors contribute to the Pirates' success?
Companies such as STATS and Baseball Info Solutions have tracked batted ball data for years, and researchers such as Mitchel Lichtman turned that data into a way of measuring how many runs range and positioning save. The idea behind Ultimate Zone Rating (UZR) is that some batted balls are easier to field than others. A ground ball at a straightaway position gets turned into an out more often than a hard hit ball in the hole. Someone who makes a play on the latter ball saves his team runs. The player who misses the former ball costs his team runs. UZR uses years of data to build a model for locations, batted ball type (fly, ground, etc.) and speed of hit balls, and compares the run value against the expected average. Based on those models the Pirates defense has saved 18 runs this season, third in the NL.
But the Pirates' ERA is 61 runs better than their FIP. So, their defense accounts for about 33% (18out of 61) of the difference between the team's FIP and ERA, implying that balls put in play against Pirates pitchers are easy to field. Is there any evidence Pittsburgh pitchers are tough to hit?
The first indication that the Pirates prevent good contact comes from their line-drive rate. FanGraphs.com shows Pittsburgh pitchers allow line drives on 19.1% of batted balls, the best rate in the NL. Like their BABIP, this is an extreme outlier:
Rank / Pitchers / Line drive pct.
1 / Pirates / 19.1
2 / Reds/ 20.2
10 / Dodgers / 21.1
As Warren Spahn said, "Hitting is timing. Pitching is upsetting timing." The Pirates upset timing in two subtle ways. First, they fool batters in the strike zone, leading to pitches being taken.The Pirates are farther above the second-place Reds than the Reds are above the 10th-place Los Angeles Dodgers. Again, is this a skill of the pitching staff or luck?
FanGraphs lists the percent of pitches in the zone on which batters swing. Pittsburgh pitchers produce the lowest swing rate, 63.6% vs. an NL team median of 66.1%. It's a small difference, one more called strike per 100 pitches in the strike zone, but it's an advantage in the right direction. The Pirates' Francisco Liriano and Jeanmar Gomez have rates below 67.8%, and own ERAs below 3.00. When batters recognize a pitch as a ball and it turns out to be a strike, they might expand their strike zone to chase pitches that are outside.
That tendency plays into the strength of the staff. The Pirates rank in the middle of the NL in getting batters to chase bad balls, as opponents swing at 30.5% of pitches outside of the strike zone. But when batters do swing, they make contact 63.6% of the time vs. an NL team median of 66.1%. The Pirates' rate is the lowest in the NL, meaning they get more swinging strikes on bad balls. It would imply that even when batters make contact on pitches outside of the strike zone, that contact is poor.
A.J. Burnett is the quintessential Pirates pitcher. Batters swing at 60.6% of his pitches in the strike zone. When they swing at an outside pitch, they make contact 51% of the time. They hit line drives vs. him 18.6% of the time, and his 3.06 ERA is well below his 3.25 FIP.
The difficulty comes in measuring how much these subtle strengths contribute to the team's low ERA. Studies show these zone rates stabilize quickly for pitchers. So as long as the pitchers keep fooling batters and the defense gobbles up balls, the Pirates have a chance to keep winning.
Pinto writes for BaseballMusings.com, an affiliate of USA TODAY Sports Digital Properties.