Halama, a New York native, was acquired as a free agent by the Nationals on Aug. 5 and has spent the last two weeks with Triple-A New Orleans. In two games, he has given up one earned run in eight innings.
Halama, 33, started the season with the Red Sox. He was mostly a reliever with Boston, appearing 30 games with a 1-1 record and a 6.18 ERA before the Red Sox designated him for assignment on July 26.
Halama has played in the Major Leagues for eight seasons. His best season was 2000, when he went 14-9 with a 5.08 ERA for the Mariners. Halama is best known for being part of the Randy Johnson trade, which sent Halama from the Astros to the Mariners in 1998.
Meanwhile, the Nationals optioned outfielder Brandon Watson down to Triple-A to make room for Halama. Watson was brought up early last week to provide a spark at the top of the lineup, but he hasn't played a game since Saturday. Watson has played in five games and is 3-for-19 (.158) with five runs.
"With [Jose] Guillen, [Brad] Wilkerson and [Preston] Wilson establishing themselves as the starting three, the 12th pitcher is more valuable than the fifth outfielder," Bowden said.
Top prospect: Bowden had hoped that he wouldn't bring up third baseman Ryan Zimmerman to the big leagues until next season, but Bowden hinted after Wednesday's game that Zimmerman may be up soon.
In fact, Bowden instructed his Minor League people to play Zimmerman at shortstop on a daily basis for Double-A Harrisburg starting Wednesday night against Bowie.
"I would like to avoid bringing him up, but we are in a pennant race. And when you are in a pennant race that is this close, and it's going to make you better, you have to do what's right for the team," Bowden said.
"He has the ability to play both short and third. It protects us at both positions as we head into September. He is a very special defensive player, with great hands and a good arm. He is going to hit and hit for power. He's probably going to be rushed to the big leagues, but that's life."
Zimmerman was the Nationals' first-round pick in the 2005 First-Year Player Draft, and Bowden wasn't at a loss for words when he compared Zimmerman to Brooks Robinson, Scott Rolen and Mike Schmidt. At shortstop, Zimmerman has been compared to Cal Ripken Jr.
"Ryan has made some adjustments to the plate since I last saw him. That's why he is hitting over .300. But winners usually learn to adjust," Bowden said.
Entering Wednesday's action, Zimmerman was hitting .315 with seven home runs and 29 RBIs for Harrisburg.
Going to Church: Manager Frank Robinson believes that outfielder Ryan Church can become a valuable pinch-hitter, but Church has to do his homework before he reaches the plate.
"It's a mindset. During the course of a ballgame, he has to keep notes on pitchers." Robinson said.
As a pinch-hitter, Church is 3-for-20 (.158) this season.
Did you know? Right-handers Esteban Loaiza, Tony Armas Jr., John Patterson and Livan Hernandez have earned wins in four consecutive games from Aug. 12 to Aug. 15.
The last time the Nationals/Expos starters nabbed the win in four straight games was July 31 to Aug. 3, 2003, when Zach Day, Tomo Ohka, Javier Vazquez and Livan Hernandez turned the trick.
Stats of the day: Entering Wednesday's action, the Nationals are hitting .457 (21-for-45) with two outs in their last three games.
On deck: The Nationals play a day-night doubleheader against the Phillies on Thursday starting at 1:05 p.m. ET The second game will start at 7:05 p.m. ET.
Tony Armas Jr. will pitch the first game. He has given up just one run in his last 11 innings. Armas will face the Phillies for the 11th time in his career. He is 5-3 with a 4.76 ERA against them. In his last start, Armas pitched six shutout innings as the Nationals blanked the Rockies, 8-0.
Drese, who will pitch the nightcap, pitched one-third of an inning against the Phillies on Tuesday before the game was postponed because of rain. Drese will face the Phillies for the third time this season. He is 1-1, 10.57 ERA against them.
In his last official start, Drese gave up six runs -- five earned -- in 5 1/3 innings as the Astros defeated the Nationals, 6-3.