PHOENIX -- There really is no way to explain it, so Brad Ziegler does not even try.
The D-backs' right-hander led all relievers in getting hitters to ground into double plays last year with 21. It was the most since Doug Sisk recorded 21 double plays for the Orioles in 1988.
"In my mind it was really bizarre," Ziegler said. "Last year I'd come in with a runner on first, and I knew I had a great infield, so I wanted to use them. It just seemed like every time they hit a ground ball right at somebody. It was bizarre for sure. I'm glad everybody else realized how bizarre it was, because every time it happened they were like, 'That's weird.' I would just shrug my shoulders."
As advanced metrics have shown, pitchers have very little control over the ball after it leaves their hands. Ziegler's goal with his submarine delivery is to keep the ball down and induce hitters to hit the ball on the ground.
Yet even if he is successful at that, the ball could just as easily bounce through the hole as into a glove.
"That was one of the hardest things for me to get used to as a submariner," Ziegler said. "I was told, 'As long as you're getting soft contact on the ground, you're doing your job. If they hit it at somebody, great, and if not you have to accept it.' Sometimes the ball is going to find a hole and get into the outfield, and the key to that is how do you react to it. What do you do with the next pitch? Do you let it fluster you or do you keep executing your pitches?"
Ziegler didn't always throw with the submarine delivery.
Drafted by the Phillies in the 20th round of the 2003 First-Year Player Draft as a conventional starting pitcher, Ziegler was released by Philadelphia the following spring.
After making four starts in the independent Northern League, Ziegler was signed by the A's, and for the next three seasons was a starter with a regular delivery in their Minor League system.
After watching the success he had throwing sidearm occasionally to finish off a batter, the A's suggested that Ziegler adopt the submarine delivery for the 2007 season. They told him that it would help him to reach the big leagues sooner and stay longer.
The move paid off, and Ziegler found himself making his big league debut on May 31, 2008, against the Rangers in Texas.
"I'm on the same field with Josh Hamilton, Michael Young and Ian Kinsler, and I'm just like, 'What am I doing?'" Ziegler said. "This is ridiculous. I was just like, 'I don't belong here.'"
However, it didn't take long for him to prove that he did.
In fact, for the first 39 Major League innings, Ziegler was unscored upon, setting a record for the most scoreless innings to begin a career.
In a lot of ways, the 21 double-play grounders last year reminded Ziegler of his rookie streak.
"I wasn't doing anything different than I normally do, and all of a sudden there's just a streak, a chain of reaction of things that all fall in line," he said.
D-backs manager Kirk Gibson has marveled at the way Ziegler consistently gets hitters to pound the ball into the ground, and while some relievers pitch better if they come in to start an inning, Ziegler is more valuable coming on when there are runners.
"With me, a guy on first base sometimes can be a weapon, because I'm still a pitch away from having two outs," Ziegler said.
Ziegler had a 2.49 ERA last season, and since coming over just prior to the Trade Deadline in 2011, he has 2.36 ERA for the D-backs.
But in the big leagues, past success does not guarantee it in the future, so Ziegler spent the offseason adding a changeup to his repertoire. Well, re-adding it is probably more accurate. He threw it in 2008 and '09, but lost the feel for it in '10.
"Hitters are constantly trying to make adjustments, and if I can throw a little wrinkle in there they have to honor that one more thing, it can make a difference," Ziegler said. "If they want to truly be prepared for the at-bat, it gives them one more thing to think about."
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB.