NATIONAL HARBOR, Md. -- The Indians know they have one of the best left-handed relievers in the game in Andrew Miller . What Cleveland would like to do this offseason is improve the level of lefty depth behind Miller in the team's talented bullpen.

The Indians took a step in that direction on Thursday, when the club wrapped up the Winter Meetings by taking lefty Hoby Milner with the 15th pick in the Rule 5 Draft. Cleveland grabbed Milner off the Triple-A roster of the Phillies and will bring the reliever to Spring Training with a chance to win a job in the Tribe's Opening Day bullpen.

"He's one of those guys who we felt was worth taking a shot on," said Indians assistant general manager Carter Hawkins, who oversees the farm system. "His makeup checked out and it certainly seemed like a guy that potentially could help us out in the Major Leagues. So, we're interested to get a better look at him."

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The Indians, who now have one vacancy on their 40-man roster, spent $100,000 to select Milner, who must remain on Cleveland's active roster all season. If the Indians want to remove the left-hander from the roster at any point, they must first offer him back to the Phillies for a cost of $50,000.

As things currently stand, the Indians' bullpen projects to include Miller, Cody Allen , Bryan Shaw , Dan Otero and Zach McAllister . There are a slew of contenders for the two or three remaining spots. The main left-handed options behind Miller include Kyle Crockett , Edwin Escobar (out of Minor League options) and Milner. Ryan Merritt , Tim Cooney and Shawn Morimando are also on the roster, but are starters by trade.

Miller held left-handed batters to a .181 average (.523 OPS) last season, while the rest of the lefties who cycled on and off the Indians' pitching staff combined to allow a .280 average (.714 OPS) to left-handed batters. That group included Crockett, Merritt, Morimando, Ross Detwiler , Tom Gorzelanny and TJ House . Cleveland's 28 1/3 left-on-left innings were the fewest in the Majors last year.

"We're definitely exploring opportunities to continue to improve our team," said Indians GM Mike Chernoff, when asked about the team's hunt for left-handed depth. "That's an area where, especially behind Miller, we have a few internal options, but clearly we could try to upgrade there also."

Milner, 25, posted a 2.49 ERA in 49 games between Double-A and Triple-A in Philadelphia's system last season. Over 65 innings, the lefty struck out 76, walked 15 and limited lefty batters to a .559 OPS. Hawkins said that Milner's work as a starting pitcher early in his career can be beneficial for facing right-handers. The assistant GM also noted that Milner lowered his arm slot toward the end of last year and had strong results.

"We feel like has a chance to be that situational-type guy," Hawkins said. "He had a lot of success as he dropped his slot."

During the Major League phase of the Rule 5 Draft, the Indians lost outfielder Anthony Santander , who was picked by the Orioles. Santander had an .862 OPS for Class A Advanced Lynchburg last season, but is currently rehabbing from offseason shoulder surgery. The Indians also lost pitchers Trevor Frank (San Diego), Nick Maronde (Miami), Jon Fitzsimmons (Arizona) and Grant Sides (Arizona) in the Minor League portion of the Draft.

"We have to make really difficult decisions, obviously," Hawkins said. "There's a limit to how many guys we can put on each roster. At the end of every reserve list filing date, you know that there's a guy who can potentially get plucked. Having this many is really just a great reflection on our Drafts and our player-development staff that, even guys we weren't able to put on rosters were being recognized by other organizations.

"We're certainly excited for those guys to get better opportunities, potentially, with other organizations, and we wish them the best, and we're glad they have that chance to make a new path for themselves."

Jordan Bastian has covered the Indians for MLB.com since 2011, and previously covered the Blue Jays from 2006-10. Read his blog, Major League Bastian, follow him on Twitter @MLBastian and listen to his podcast.