"Though Sunday's non-waiver trade deadline is approaching, General Manager Kevin Towers says the "lightning round" of trading season has yet to begin.

But when it does, he expects the Diamondbacks to be able to land a reliever who can help them not only in the season's final two months but also in 2012. It might cost them more in terms of talent, but Towers sees it as a hole they'll have to plug at some point anyway.

"Our hope would be that if we make a deal, to have somebody who'd be here beyond this year," he said. "If not, we're going to be out there this winter looking for that guy once again."

Towers reiterated that the club's focus remains on pitching, though he didn't rule out acquiring a position player if the "right deal presents itself."

The Diamondbacks still appear determined not to part ways with any of their top prospects, namely pitchers Jarrod Parker, Tyler Skaggs, Pat Corbin and David Holmberg and first baseman Paul Goldschmidt. According to a source, the club balked when the Houston Astros asked for that caliber of player when discussing a deal for left-hander Wandy Rodriguez.

When asked what area he considers to have the best depth in his farm system, Towers cited corner outfielders and infielders.

That could mean the club would be willing to part with a prospect such as Bobby Borchering, Matt Davidson, Ryan Wheeler or even Collin Cowgill, who was promoted to the majors on Tuesday."