Since Larry Rothschild took over as the Yankees pitching coach, the staff has been defined by two distinct factors - a revolving door (largely due to injuries), and effectiveness. It seems almost nonsensical that a pitching staff can thrive with nary a hint of stability, but the Yankees did just that in 2014 (having used 33 pitchers), and they're doing it again now, despite 30 players having thrown a pitch to date (including Garrett Jones). The team currently ranks 5th in the Majors in K%, 6th in K-BB%, 9th in FIP-, 9th in fWAR, and 11th in ERA-. It is, by most metrics, a top-ten pitching staff, and it is right in-line with last year's performance ... save for a notable increase in groundballs. As of this writing, the Yankees sit sixth in the Majors in GB%, with 47.4% of batted balls burning worms. This represents a high-water mark for the team by a significant margin - with the exception of 2008 (47.0%), the team has not eclipsed the 45% mark for a long as this particular data has been tracked, beginning in 2002. Newcomers Andrew Miller (51.8%), Nathan Eovaldi (51.8%), and Justin Wilson (49.5%) all pick up grounders at a well above-average rate, and Michael Pineda's 50.9% mark is more than ten-percent higher than his career norm heading into this season. And with Ivan Nova finding his groove, the Yankees have induced more and more grounders as the season wears on (their 50.3% GB since the break is the best in the Majors).
Interestingly enough, it is difficult to find a root cause for this - the Yankees are near the bottom of the Pitchf/x list in two-seamer and sinker usage, and a cursory look does not suggest that they are utilizing the bottom of the strikezone with greater frequency than the last few years (though it has ticked up a bit). Whether it is a blip or some greater strategy that eludes me, it is certainly a positive trend. Ideally, more ground balls means fewer base extra base hits (particularly home runs), and more opportunities for double plays. And as the defense improves, this may help give the staff a leg up as it pushes through another few weeks without Pineda.