HOUSTON -- The Pirates' deal for left-hander Wandy Rodriguez, further bolstering and overstaffing a team strength, was a move that puzzled many. It may become easier to understand as the days wind down towards Tuesday afternoon's non-waiver Trade Deadline.

Rodriguez -- slated to debut with the Pirates against his old team, the Astros, on Saturday -- becomes the Bucs' sixth starter. The Pirates do not intend to keep a six-man staff. General manager Neal Huntington remains on the prowl for a three-dimensional outfielder (bat, glove, legs).

The expectation is that the Rodriguez acquisition set in motion a deal in which another starter would be dealt for the outfielder the Pirates need.

Starling Marte's long-awaited Major League promotion supports that possibility. His arrival five days prior to the Trade Deadline is not coincidental.

Calling up the franchise's No. 3-rated prospect tells the teams Huntington is negotiating with for outfielders, "Fine, if you don't budge on the acquisition cost, we can find help internally."

None of the impressions made by Marte in the next few days will be permanent, yet Clint Hurdle's staff may see enough to reach a quick conclusion as to whether, in the short term, outside help is needed.

And if Marte takes the big leagues by instant storm and becomes a quick fixture? Then Huntington can shift his attention to the veterans Hurdle desperately wants for his bench.

This much is clear: the Pirates have plenty of young pitchers to use as trade chips. The inclusions of lefties Rudy Owens and Colton Cain in the Rodriguez deal (along with outfielder Robbie Grossman) hardly put a dent into the stash.

Minor or Major League pitchers could be dealt, but prying someone out of a Pirates uniform will be more costly.

The possibility of Joel Hanrahan and his 30 saves going in a blockbuster has been on the back burner all summer. Many elite teams that lack a proven closer would be willing to swap two Major League bats for him. The Pirates may feel confident giving the closing role to Brad Lincoln, Jason Grilli or a combination of the two of them.