In the sixth inning of Tuesday's game, against Phillies second baseman Chase Utley, Mattheus threw a pitch right down the middle, and Utley connected for an RBI single.
"Everyone can look at the numbers and know that they are not good, and I'm the first to say they are not good," Mattheus said. "When I break it down and I look at it, the one glaring thing is pitch location. Whether it's something mechanically or something mentally, it's not allowing me to get the ball where I want it. The bottom line is, I'm not making pitches.
"I would like to think my best attribute is mental toughness and being competitive. The only thing I can do is address the problem, and that's pitch location -- go out, compete my [behind] off and fix it."
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the Time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.