Weak D

In a 2-part study in 2011 here and here, I looked at the best and worst team defenses, measured by their Defensive Efficiency Rating (percentage of balls in play turned into outs) relative to the league average. (This is not a park-adjusted measurement, so park effects do play into this).
Let’s look at this year’s contenders, as well as updating the 2011 charts, which were based on early season results. As I explained in the longer article, it is extremely rare for teams to finish 5% or more above or below the league average – the 2007 Tampa Bay Devil Rays, at 95.32%, were the least effective defensive team in the postwar era (they led the AL the following year, which accounted for almost the entirety of their improvement to a pennant-winning team), while only three teams in that era cracked 105%: the 2001 Mariners (tops at 105.52%), 1999 Reds, and 1975 Dodgers (yes, that’s two teams with Mike Cameron in center field). The last team below 95% was the epically awful 1930 Phillies, the last below 94% was the 1899 Cleveland Spiders, who finished 20-134. The 1930 Phillies were also the only team since 1915 to convert fewer than 65% of all balls in play into outs.
Here’s the decade in progress, through June 22, 2012:
National League

A couple of things jump out when looking at the NL. First, balls in play are way down this year; the NL in 2010 was the first league ever below 70%, and this season’s average would be a historic low. But team defense is also off from 2011.
As far as team defense, the Nationals’ surge this year may owe a lot to the “K Street” pitching staff that is averaging 8.4 K/9, but the team has also featured the NL’s best defense since the 1999 Reds, beating every NL defense of the past decade by a full percentage point (if they can sustain this pace). At the opposite end of the scale, the Rockies are currently threatening to be the first team since the 1899 Spiders to run below 94% of the league average and the first since the 1930 Phillies to post a DER below 650 (the team opposing batting average on balls in play – BABIP – is an eye-popping .343; there are a few accounting reasons, such as double plays, why DER and BABIP are not precise mirror images). Two of the team’s top relievers, Esmil Rogers and Rex Brothers, have been pounded to the tune of BABIPs above .400, although Brothers has survived this by striking out 35 batters in 24 innings and allowing only one home run.
Regression to the mean is likely for both the Nats and the Rockies, and Colorado in particular is likely to tinker with its lineup to fix the problem (this is what the Astros did after a similarly horrific defensive start in 2011).
American League

In the AL, the league DER dropped off sharply from early June 2011 – when I wrote last year’s post and the league average was 702 – to season’s end at 694, leaving the Rays (who slightly improved their DER) with the best defense relative to the league (and in absolute terms) since 2001. Meanwhile, the Twins’ defense collapsed, moving the White Sox out of last.
Turn to 2012, and the White Sox are now atop the AL, and Tampa at 696 is just a hair below the league average. But it’s the Tigers who horrify, with an Opening Day infield of Prince Fielder at first, converted outfielder Ryan Raburn at second, lead-footed Jhonny Peralta at short and Miguel Cabrera – who is not significantly thinner than Fielder – at third. Even the spectacular center field defense of Austin Jackson can’t salvage this D. Raburn, hitting just .165/.225/.245, has largely been supplanted now by Ramon Santiago, but Cabrera, Fielder and Peralta aren’t going anywhere. This presents a real problem. The highest BABIP ever recorded (since such things have been tracked; at present the records go back to 1948) against a pitcher to qualify for the ERA title was .358 vs Kevin Millwood 2008 (four of the ten worst were Texas Rangers – besides (Millwood, you can find Kevin Brown, Aaron Sele, and John Burkett on the list). THis season, you have Max Scherzer at .383 BABIP, Josh Johnson of the Marlins at.365, and Rick Porcello at .350 (no Rockies qualify). Even with some expectation of a regression to the mean, the BABIP vs the whole Tigers staff is .318, so Scherzer and Porcello can expect to struggle with this all year. This is a major reason why Scherzer has a 5.17 ERA despite striking out 11.5 men per 9 innings and a K/BB ratio of 3.45 to 1 (Scherzer has also had home run problems), and Porcello a 4.95 ERA despite allowing just 2.3 walks and 0.9 HR/9 and a 2.3 to 1 K/BB ratio. The 1983 Phillies were the first team ever to finish in first place with the league’s worst DER; it’s been done twice again since (the 1998 Rangers and 2001 Indians), but for a team that was projected as the division leaders based on their offense (which, granted, is 7th in the league in runs) and pitching, that may prove too heavy a burden to carry.