Jayson Werth. (AP Photo/Nick Wass)

The Nationals’ offense has hit well enough this month to help power the team to a 13-8 record entering Tuesday, the only NL East team with a winning record in June. But there is a underlying theme through the entire season, including this month, about the Nationals’ offense: they have trouble hitting breaking balls.

Entering Tuesday’s game, according to numbers at BaseballSavant.com, the Nationals were hitting .199 against breaking balls. That average ranks sixth-worst in baseball, behind the Padres, Mets, Red Sox, Astros and Giants. The Nationals, on the other hand, have done better against fastballs and fastball-type pitches, such as sinkers and cutters, posting a .264 average against them, good for the 18th-best mark in baseball.

Nationals Manager Matt Williams has noticed and believes it is a matter of plate discipline. The Nationals are chasing breaking balls outside the strike zone more than they should.

“It’s a question of good breaking [balls] as opposed to bad breaking balls,” he said. “Breaking balls for strikes are good to hit. Breaking balls out of the strike zone nobody hits. If we’re aggressive and overly aggressive and we’re swinging at balls out of the strike zone, generally that’s not a fastball. More times than not it’s either a change-up, curveball, slider, something other than a fastball. So I think that speaks to the numbers.”

While the Nationals preach a hitting approach of attacking fastballs, they have done better against breaking balls in the past. Last season, the Nationals hit better against breaking balls, posting a .217 average, good for 11th-best in baseball. In 2012, they had the sixth-best average, .232, against breaking balls. That production has slipped so far this season.

“I think it’s swinging at strikes,” hitting coach Rick Schu said. “A lot of the breaking balls we’re swinging at are balls. … Sometimes you have to tip your cap, shorten up and make adjustments. Just try to get them over the plate and see the ball up, and don’t swing at balls.”

The Nationals’ regulars that have struggled with breaking balls this season are Ian Desmond (19 for 107, .178), Jayson Werth (15 for 83, .181) and Jose Lobaton (3 for 26, .115). Denard Span (13 for 55, .236) and Anthony Rendon (17 for 72, .236) have had mild success against breaking balls. Danny Espinosa  (12 for 46, .261), Adam LaRoche (11 for 39, .282) and Ryan Zimmerman (8 for 27, .296) have been the team’s best hitters against breaking balls.

Werth and Desmond are the anomalies so far this season. In his stellar 2013 season, Werth hit .249 (37 for 149) against breaking balls. Desmond, who has hammered curveballs in the past, hit .268 (53 for 198) against breaking balls last season. They both did well in 2012, too; Werth hit .283, and Desmond hit .251 against those pitches.