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The Baltimore Orioles appear to be turning to Plan B after reportedly balking at the asking price for left-hander Jon Lester.

According to Jon Heyman of CBSSports.com, the Orioles have focused their attention on Houston Astros pitchers Dallas Keuchel and Jarred Cosart in an effort to bolster their rotation at the trade deadline.

Baltimore possess four of the top prospects in baseball, but a source within the organization tells Heyman the Orioles are reluctant to part with them in a deal for Lester.

The Orioles wouldn't relinquish top prospects Kevin Gausman, Dylan Bundy, Eduardo Rodriguez and Hunter Harvey to rent a pitcher, even a great one like Lester. "It's a 56-game rental," one Orioles person pointed out.

It seems unlikely, however, that the Astros would deal Keuchel or Cosart without netting a solid return, given both pitchers are under team control for the next several years.

Keuchel, a 26-year-old left-hander, leads the club with a 3.11 ERA and 127 1/3 innings pitched. His team-best 3.02 FIP ranks 11th in the American League.

The 24-year-old Cosart has had an up and down rookie year but the right-hander is second on the Astros with 116 1/3 innings and has produced quality starts in over half his outings.

While Cosart doesn't offer the Orioles an immediate upgrade at the back end of their rotation, Keuchel would likely be the top arm on the staff.

Here's a look at how both starters compare to Baltimore's current crop of arms: