Rule 5 draft rumors: Astros prospect Roberto Pena a target for Arizona at No. 1

In a time before free agent relievers ruled our existence, we cared about the Rule 5 draft. We cared about which players Houston protected on its 40-man roster and the decisions they made on who to leave off.

It appears that time could be returning. Jim Callis of MLB.com is reporting that the Diamondbacks have interest in a surprising Astros prospect in Thursday's Rule 5 draft.

Rule 5 rumblings that @Dbacks might take @Astros C Robert Pena w/top pick. VG defensive C w/questionable bat.

— Jim Callis (@jimcallisMLB) December 10, 2014

Pena, 22, hit .249/.306/.414 last season with High A Lancaster. The 2010 seventh-round draft pick has a sterling defensive reputation but there are concerns about his bat. In 1,522 career minor-league plate appearances, Pena has hit .238/.284/.346 with 26 home runs and 255 strikeouts.

Last season, the White Sox plucked a similar player, Adrien Nieto, away from the Nationals and installed him as their backup catcher. Nieto, 24, hit .236/.296/.340 in 118 plate appearances for the White Sox.

Evan Drellich talked with Jeff Luhnow on Tuesday about the Rule 5 and heard that the Astros do not expect DDJ to be drafted.

Luhnow said he did not think a team would take DeShields, however. He hit .236 with a .346 on-base percentage and 11 homers.

"It's a tricky thing," Luhnow said. "You never know which teams are going to like which players and what they're looking for. But it is difficult to keep a Rule 5 player all year long."

A quick overview: the Rule 5 draft is for players who have been with their teams for either four or five seasons, depending on how old they were when they signed, but who have not been placed on a 40-man roster.

Drafted players must stay on a 25-man roster for the entire season and the player must remain active (not on the disabled list) for at least 90 days. If a player gets demoted or doesn't meet this requirement, he must be offered back to the original team.

Teams with open spots on their own 40-man can draft players. It functions much the same as the June draft does, with the order being determined in reverse of last season's finish.

That gives the Diamondbacks the first overall pick. Rule 5 players can be traded immediately after being drafted, which is what happened last season, when Houston traded its first overall pick to the Padres for reliever Anthony Bass.

The draft will be held Thursday morning, beginning at 11 p.m. CST.