Entering Tuesday's action, Espinosa, who will be on the U.S. roster, was hitting .249 with nine home runs and 26 RBIs for Double-A Harrisburg. Entering the 2010 season, Espinosa, 23, was ranked as the Nationals' fifth-best prospect by Baseball America.
"I think it has been kind of two seasons for him," Nationals farm director Doug Harris said. "I think he had some growing pains early on. He has really turned it around -- both offensively and defensively. It has gotten to a point where he made adjustments on both sides of the ball. He has a chance to take off."
Perez, who participated in Jordan Zimmermann's simulated game on Tuesday, is hitting .257 with a home run and 18 RBIs for Class A Hagerstown. Not bad considering that he was in the Gulf Coast League last year, skipped Class A Vermont and then made the jump to Hagerstown this year. Perez, 20, will play for the World Team. The Nationals hope he can be a leadoff hitter in the future for the club.
"It has been a great year for him," Harris said. "He started the year hitting .210. and is now in the .250 range. It shows that he has made strides. He can really play defense."