Chen Music


Jul 23, 2013; Kansas City, MO, USA; Kansas City Royals starting pitcher Bruce Chen (52) delivers a pitch in the first inning against the Baltimore Orioles at Kauffman Stadium. Mandatory Credit: John Rieger-USA TODAY Sports

Bruce Chen is on fire.

Since being inserted into the rotation for Luis Mendoza, Chen has gone 2-0 with a 1.14 ERA. 1.14! He’s struck out 23 batters in 31.2 innings pitched, which to be honest is way more strikeouts than I thought he’d produced. He’s pared that with only walking four batters and 16 hits allowed. That’s amounts to a 0.632 WHIP.


It is not like Chen’s stuff has been great either. His average fastball speed has been 86 mph, and his slider has been slower than his changeup. He’s getting decent movement on his pitches, but hitters are certainly having enough time to read what is coming at them.

I can’t explain how he is doing this, and I’m totally fine with it. But if I had to make a guess it would simply be that he is playing chess better than the batter’s he is facing. Chen is moving the ball over the place, and is taking advantage of the great defense around him. Through his five starts he has a line drive percentage (19) that matches his pop-up percentage (19). Hitters are guessing, and for the most part they are guessing wrong. And when they do guess right, batter’s are hitting it at Royals defenders.

Evidence for this can be found in his pitch usage. Here is the general breakdown of pitch usage he’s had in his five starts:

Sinker: 28.36%

Cutter: 27.12%

Fourseam: 18.63%

Curve: 11.8%

Change: 11.39%

Slider: 2.69%

One, that’s a lot of pitches Chen has in the arsenal. And two, Chen has thrown a breaking ball more often than either of his fastballs. This is very interesting to me, because one would think he would be using his fastball more often to get ahead in counts. Apparently he really trusts his sinker.

The other thing of note is when he uses his pitches. Look at the chart below.

The diversity of pitches against right-handed batters as compared to the simple approach against lefties is surprising. Chen has been more predictable against left-handed batters than he has righties, against whom he is as likely to throw a curveball on the first bit as he is a fastball. The unpredictability against right-handers has kept them off-balance enough to get outs.

Lefties have been different. Chen seems to be very comfortable with his cutter, which tails away against left-handed batters, and pounding his sinker to get ground balls. His lack of throwing the changeup against left-handers makes me think he feels very confident in getting lefties to ground out against his cutter and sinker, which makes a lot of sense since he seems to believe in his infield defense.

I don’t expect Chen’s dominance to continue. He’s benefited from throwing a lot of strikes and an insanely low .157 BAbip during this stretch, and for the season he’s been lucky with fly balls not turning into home runs – 5.9% HR/FB this season, 11.8% for his career. Also, Chen’s 1.79 ERA for the season does not match up well with his 4.68 xFIP, which suggests he benefitted heavily from luck and defense.

But, hey, it’s better to be lucky than good, right? Hopefully his luck continues for at least two more months.