Garza and Castro, probably the only sure bets to be with the Cubs in future seasons, turned up their play during the recent seven-game winning streak.
On Monday, Castro was named the NL player of the week. In his last seven games, Castro had 17 hits and is currently third in the majors with 150.
"Good for him. Hopefully it will be a long list of accolades for him. If he keeps his head screwed on and keeps getting better he will be fun to watch for a lot of years," Cubs manager Mike Quade said before Monday's game against the Washington Nationals was postponed because of rain.
The game will be made up Thursday at 1:20 p.m. Both teams will continue with its current pitching rotation. Garza and Chien-Ming Wang, Monday's starters, will be pushed back to Tuesday night.
"Given the situation, given the way he's performed, yeah, right now he's the lone viable option," Quade said.
The only real concern for the 21-year-old shortstop is his play in the field. He has committed 18 errors this season, but Quade has seen some improvement in that area.
The Cubs didn't win three straight all season until July 22-24, then Garza extended the winning streak to four games Wednesday with a 1-0 victory at Pittsburgh. Garza (5-8, 3.78 ERA) went seven-plus innings, striking out seven and allowing four hits for his first win since June 27.
The right-hander has an ERA below 4.00 despite losing eight games.
"I just know if you're going to win baseball games guys need to pitch well. It doesn't guarantee a win, but it should guarantee you a chance to win," Quade said. "I just assume focus on the quality he is running out there on a quality basis and believe with that going on the wins will take care themselves at some points, but he hasn't been lucky that's for sure."
A forecast of steady rain throughout the night prompted the Cubs to delay the opener of the three-game series. The game was called after a 32-minute delay.
Wang is scheduled to make his third start of the season -- and first on the road -- Tuesday after missing more than two years following shoulder surgery.
Nationals manager Davey Johnson thinks being pushed back will be beneficial for Wang, who made his last start Wednesday.
"I know he had an extra day in one of his rehab starts down in Syracuse. He threw good. So, it probably won't hurt him," Johnson said.
Tickets for Monday night's game will be honored on Thursday. ... In his last outing Wang surrendered six runs -- two earned- in five innings in a 6-4 loss to Atlanta. He threw 86 pitches.