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8/24/2014 1:36 P.M. ET

Introducing sinker, Miller keeps focus on improving

PHILADELPHIA -- Shelby Miller is still young enough to be building for his future. The 23-year-old starter for the Cardinals has had some ups and downs over the past three big league seasons, but he's always kept an eye down the road and has always been open to experimenting with new pitches.

The reality is, Miller has plenty of room to improve, and the Cardinals like the fact that he's looking to do just that, no matter what the calendar indicates should be the focus.

That openness to change was on display Saturday night at Citizens Bank Park, where he got the start against the Phillies in St. Louis' 6-5 win in 12 innings. Miller allowed three runs in six innings and used a sinker to great effect.

"Well, I started throwing a sinker," said Miller when he was asked about the exceptional movement he had on his pitches. "For what it is."

Miller's sinker is far from perfected, but he effectively used it on a night he allowed five hits, walked two and struck out three.

"Those side sessions, flat grounds [they throw] and the work they do over four days are important," Cardinals manager Mike Matheny said. "Sometimes it's about maintaining, and other times you are working on something. He was working on something, which is impressive for late August. To try and add a new pitch towards the end of the season is commendable. He knows he needs to make small adjustments. This could be a big thing for his career. He still has room to grow, but it's a bold step."

"I tried [Justin Masterson's] grip, and I threw it in my last bullpen," said Miller, who is 8-9 this season. "As a staff, we liked it. We talked throughout the week how to use it. The key for me is to just throw it. It's a pitch that has to progress."

Worth noting

• Matt Carpenter entered Sunday's game with a seven-game hit streak. In that stretch, Carpenter -- who has been the leadoff hitter in 127 of the Cardinals' 129 games, including Sunday -- is hitting .367 (11-for-30).

• The Cardinals won in their final at-bat for the fifth time this month on Saturday. It's the most in one month since they won five straight in September 2011.

• The Cardinals entered Sunday going for a series win in Philadelphia for the first time since 2006.

Michael Radano is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.