Breaking down Danny Duffy's last start

Kansas City Royals starting pitcher Danny Duffy turned in one of the best starts of his career on Wednesday, holding the Minnesota Twins scoreless for 6 2/3 innings. The southpaw allowed five hits, struck out seven and walked none, the first start in Duffy's career with zero walks.

Duffy looks like he will finish out the season in the Royals starting rotation. Kansas City finally moved Wade Davis into the bullpen, and Duffy will start in his place.

The lefty is an important piece for the Royals moving forward. Duffy is still young and under team control, so he should be contributing to the team beyond 2014. He has also flashed swing-and-miss stuff, giving him the potential to rack up a high number of strikeouts if he can stay healthy for an entire season.

I decided to dive into Duffy's Pitch F/X data from his previous start to see what worked for him against Minnesota, and what he can still improve upon.

Duffy's raw stuff has looked fairly impressive since his original promotion, and Wednesday's performance was no different. He throws a hard fastball, especially for a lefty, and can change speeds effectively with a curveball and a changeup.

Below is a table of the pitches Duffy threw against the Twins, courtesy of Brooks Baseball:

Duffy is still throwing his fastball at impressive speeds, which is a good sign in his recovery from Tommy John surgery. He also did a good job mixing his pitches, which helped keep the Twins off-balance.

The Strike% from his previous start is more impressive than his velocity. Duffy recorded strikes on at least 50% of his pitches, regardless of what he thew. Overall, 73 of Duffy's 103 pitches went for strikes, a cool 71% Strike%.

Duffy also did a good job forcing swing-and-misses, especially on his fastball. When an opposing teams whiffs on 23.4% of the fastballs thrown, you know that the stater was throwing an impressive game. The Twins whiffed on 15% of Duffy's offerings, a SwingingStrike% well above league-average.

The 24 year-old also maintained his velocity fairly well throughout the start. Duffy saw his velocity start to slip a little at the end, but could still throw his fastball at 94 mph around pitch 100. Below is a velocity chart, also from Brooks Baseball:

The chart also illustrates why Duffy can be tough to hit; anyone who can change velocities as well as he can will make timing his pitches a challenge for the opposition.

Duffy's start against Minnesota reveals a few things that he can work on, specifically the location of his pitches. He still thew a number of pitches outside the strike zone that a more disciplined team may have not have chased as frequently, and located a number of pitches up in the zone.

It's possible I need to title this post "Brooks Baseball is the Greatest," since they are providing the following chart as well:

When Duffy misses, he tends to miss well out of the strike zone. This has been true throughout his young career, and his previous start was no different.

A number of the pitches that Duffy completely missed the strike zone with were the first pitch of the at-bat; I counted 10 on a different chart that landed well outside the strike zone. That means Duffy threw 14 first pitch strikes or borderline strikes, which is still solid. Given the lefty's penchant for working long counts, it would be nice to see him not miss so dramatically on the first pitch of the at-bat and work from behind.

For the most part, however, Duffy peppered the strike zone. Unfortunately, he spent much of his time up and over the plate, with the majority of his pitches landing in the upper 2/3 of the zone. Duffy's stuff can help off-set some of the location issues, but too many pitches landed over the middle of plate. A better team than Minnesota would have likely jumped over some of Duffy's mistakes and plated a few runs.

Duffy's stuff continues to impress and he achieved some strong results Wednesday night, but there are still some issues with his command. It's nice to see him throw strikes, but he will need to throw more high-quality strikes in the future to achieve similar results against better teams. Either way, it's nice to see Duffy back in the starting rotation and contributing to a Royals win.