Parnell credits knuckle-curve for success

PORT ST. LUCIE, Fla. -- Bobby Parnell credits much of his recent success -- and the resulting ninth-inning duties that he is on track to obtain -- to the knuckle-curve Jason Isringhausen taught him back in 2011. Initially fooling with the pitch late that year, Parnell committed to it during Spring Training 2012 as he scrapped his slider altogether.

It's a valuable pitch, yet advanced metrics reveal that Parnell's slider was actually a more effective offering than his knuckle-curve. That Parnell improved his overall numbers in 2012 was thanks in large part to some much-improved control, and also to a better fastball.

So what gives? Pitching coach Dan Warthen said Parnell's fastball has become a more effective weapon due to a greater separation of velocity between it and his breaking ball. Whereas Parnell used to throw his primary breaking pitch in the upper-80s, he now throws his knuckle-curve in the lower 80s. As a result, hitters have a more difficult time adjusting from one pitch to the other.

"The spread of velocity always works," Warthen said. "It's a big difference, a seven- or eight-mile an hour difference."

Warthen also noted that Parnell tends not to throw many flat knuckle-curves, which had been an issue for him with the slider.