KC Royals: Danny Duffy Dominance Fueled By New Pitch

KC Royals pitcher Danny Duffy ran his record to 11-1 on Sunday, winning his tenth straight game. He’s second in the AL with a 2.66 ERA, first in winning percentage, and first in WHIP (Walks + Hits/IP). His sudden dominance is mostly due to a new breaking pitch.

Duffy’s 11-1, 2.66 ERA in 138.2 IP comes after he came into the season with a career 24-30 record and 3.80 ERA.

According to Kansas City Star writer Rustin Dodd, Danny Duffy discovered a new way to throw the breaking ball when he was fooling around in the outfield during workouts before the American League Championship Series against the Blue Jays. At the time, former starter Duffy had been moved to the bullpen due to his inability to last deep into games.

Duffy was throwing in the outfield with fellow pitcher Kris Medlen trying out a new breaking ball that he held exactly like his fastball. The ball showed a nasty, late break that caused Medlen to say:

"“Dude,” Medlen said. “You got to use this in the game.”"

Danny Duffy told Dodd that the reason the pitch is so effective is that it resembles his fastball:

"“They have to respect the fact that it’s coming out of the same grip, the same slot, the same plane as my fastball,” Duffy says. “But it’s got a last-second drop to it.”"

Duffy honed the new pitch during spring training and in a short stint in the bullpen to begin the 2016 season. Along with his new pitch, KC Royals manager Ned Yost also credits the mindset that Duffy developed as a reliever with his current success:

"“That’s when the light bulb kind of went on,” Yost says. “‘I got a good fastball. I can get guys out.’ ”"

Duffy stopped trying to nibble at the corners and instead attacked hitters. Rather than trying to pace himself through games, he let it rip with the fastball. The result has been a guy who can last deep into games with an outstanding 5.13 K/BB (Strikeout/Walk ratio).

Brooks Baseball data bears out the above assessment. Duffy’s fourseam fastball is averaging a career-high 95.88 mph, up from 94.51 mph in 2015 and 94.17 mph in 2014.

Duffy has junked his inconsistent slow curve, and is now throwing his slider 21.23% of the time after using it 13.74% of the time in 2014. He’s also upped his change-up usage to 15.81%, up from 9.67% in 2015.

The new pitch mix has increased Duffy’s whiff percentage across the board:

                                  2015             2016

Fourseam               9.32%           14.41%

Sinker                      7.93%            9.27%

Change                   11.35%          20.75%

Slider                       10.63%         15.93%

No wonder Danny Duffy’s strikeout rate has zoomed to 27.6% from 17.4% in 2015.

Next: Danny Duffy Out-Duels Ervin Santana For 2-1 Win

In many way’s, Danny Duffy’s transformation fits a typical pattern. A sudden jump in performance for a pitcher frequently follows after he adds a new, effective pitch. With Danny Duffy, the new breaking pitch took a guy that didn’t strike out many batters, despite being able to throw 97 mph, and turned him into an ace.