Against Starting Rotation, Opponents’ Plate Discipline Vanishes

Past the 50 game-mark, it’s time to—ever so slowly—place the small sample size disclaimers in the rearview mirror and appreciate the corps of young arms that has single-handedly made this Phillies team not only watchable, but an above .500 ball club for the vast majority of the season despite a wholly depressing offensive effort.

The rotation, averaging just over 25-and-a-half years old on the second-youngest team in the bigs (averaging 27.4 years old), ranks seventh in the league in WAR (5.6) even after coming back to down to earth a bit in the last handful of weeks. With surprising depth, it is believed the starters have sped up the rebuild by as much as a full year. But, while the jury is still out on the exact timetable, it’s important to note just how this rotation is succeeding without much major league experience—besides elder statesman Jeremy Hellickson, six years removed from winning the American League Rookie of the Year—or overpowering arms.

Vincent Velasquez is the lone exception to the latter, whose average fastball velocity of 94 is the fastest for any consistent Phils starter since 2002 (the first year FanGraphs began tracking pitch speed).

But for the most part, it’s not piping hot velocity that’s shutting down opposing hitters. The reason for the rotation’s success has been quite simple: combined with a high strikeout rate and a dearth of free passes allowed, Phillies’ starters cause their opponents’ plate discipline to all but evaporate when they step in the box. This leads to hitters making very little contact, and even when they do, they don’t square up the ball.

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Philadelphia’s rotation held both the third-best strikeout (23.9%) and walk rates (6.2%) in the league prior to Tuesday’s action. Their 17.4% K-BB% ranks only second behind the Dodgers, whose numbers are highly skewed by the otherworldly performance of Clayton Kershaw (105 strikeouts, five walks).

To say that hitters make very little contact against the red and white pinstriped starters is oversimplifying it. To be more precise, hitters rarely attack pitches in the zone and often swing at balls out of the zone. It is through that ideal mixture, a reluctance to swing at strikes and an overeagerness on pitches outside the zone, that has contributed to their early success. What’s more impressive is that starters one through five can successfully evaporate opponents’ discipline at the dish, and the rotation’s numbers aren’t skewed drastically by any Kershaw-ian level heroics.

Against only the Dodgers’ rotation (63%) do hitters swing at a lower percentage of strikes than those facing Philadelphia’s young hurlers (63.2%). The Phillies had led the league in Z-Swing% (percentage of strikes swing at) for much of the young season. The poster child for low Z-Swing%, Aaron Nola’s supreme command and above average movement prove a deadly combination. Opponents keep bats planted on their shoulders on 54.5% of all strikes the right-hander throws, the lowest percentage in the majors of all qualified pitchers.

Pitches in the zone that hitters lay off of typically fall into two categories: either the batter was fooled on a pitch that just catches the edge of the zone (see Nola’s fastball that darts from the left-handed batters box toward the bottom corner of the zone to a righty) and “pitcher’s pitches,” well located offerings that are difficult to put in play.

In their own ways, each benefits pitchers differently. The former means that hitters are fooled with good movement, and the initial trajectory—right up until it nibbles at the plate—doesn’t scream ‘hit me’ to opposing batters. The latter quintessentially indicates a pitcher executing his arsenal.

The rotation also elicits the fourth-highest O-Swing% (percentage of balls outside the zone that hitters swing at) in the majors at 29.9%. Just over a third of Hellickson’s offerings outside the zone are swung at, the fourth-highest rate in the league among qualified pitchers behind only Noah Syndergaard, Zack Greinke and Matt Harvey.

On balls offered at in the zone, hitters make contact 83.7% of the time (Z-Contact%) against the rotation as a whole, good for second-lowest in the majors. Both Velasquez and Hellickson rank in the league’s top 10 in Z-Contact%, with Nola just behind ranked 21.

On pitches out of the strike zone, opponents make contact just 61% of the time, the fourth-lowest mark of any rotation.

Those low contact numbers combine for the second-lowest overall Contact% of any rotation in the majors, again, only behind the sterling rotation of the Dodgers. At least in part, the high rate of swings on hard to reach pitches is a factor in their 11% swinging strike rate, second in the league behind, you guessed it, the Dodgers.

Those numbers in and of themselves are telling. But when each starter’s numbers are broken down for each respective stat mentioned above, the true depth of the rotation is fully revealed.

No more than one current Phils starter posts worse than league average numbers in any statistical categories shown above denoting plate discipline. The two youngest arms, Nola and Velasquez, are better than or equal to league average in each and every single one.

PD by Starter We know that contact made outside the strike zone results in balls put in play at lower velocities, and typically means lowered offensive production. So it’s no surprise that the rotation allows the fifth-lowest percentage of hard hit balls and third-highest rate of softly hit balls, according to FanGraphs.

While hard/soft hit data can at times oversimplify things, it’s undeniable that rarely allowing opponents to make solid contact and often inducing weak batted balls is beneficial. No doubt, some of this is due to the rotation’s ability to prompt swings on pitches outside the zone.

The most impressive aspect of the rotation’s ability to turn hitters against themselves is the top-to-bottom execution despite a lack of experience facing major league hitters. Remember, this is the first full season as a starter in the majors for four-fifths of this rotation (Adam Morgan began to pitch every fifth day in late June 2015). While each has run into their own individual troubles at times, the formula employed by all five starters thus far implies good command of the zone and an ability to use their strengths to make hitters get themselves out, both positive indicators as we near the one-third mark of the 2016 season.

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1 comment

  1. Brad Engler

    June 01, 2016 01:46 PM

    Really good analysis. Thanks.

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