Twins prospect Eddie Rosario has informed his winter ball team that he has been suspended for 50 games after testing positive for a banned substance.

According to a report on sportlivepr.com, Rosario contacted his team, Mayaguez in the Puerto Rican League, about the suspension and told GM Frankie Thon: "I have some bad news." The second baseman told Thon he took some pills to help treat an injured arm and failed a drug test because of them.

Major League Baseball announces all suspensions, but spokesman Michael Teevan wrote in an e-mail that, "we only announce discipline once matters have been resolved."

There's a chance the suspension is under appeal. MLB wouldn't announce anything until that process in concluded.

Because the league is not announcing anything now, the Twins aren't saying anything, either.

"I cannot comment on that right now," said Brad Steil, Twins director of minor leagues.

So why did Rosario inform his club? Thon, in the report, said Rosario thought the suspension included winter ball. It does not, and Rosario was expected to be in uniform Tuesday night when Mayaguez played Santurce.

The suspension will knock him out of the first 50 games of the minor league season.

It's a setback for Rosario, 22, ranked the seventh-best Twins prospect by Baseball America before the season. A fourth-round pick in 2010, Rosario began his career as an outfielder but agreed to switch to second base in 2011. Last season, Rosario batted .329 in 52 games at Class A Fort Myers and .284 in 70 games at Class AA New Britain.

The Twins sent Rosario to the Arizona Fall League, where he batted .238 in 20 games. Rosario still could open the season at Class AAA Rochester but now won't be able to play until Game No. 51.

Twins return player to be named later

The Twins sent back righthander Duke Welker, the player to be named later in the Justin Morneau trade, to Pittsburgh for lefthander Kris Johnson. It's OK to scratch your head.

Actually, Twins General Manager Terry Ryan sought out Pirates GM Neal Huntington during the GM meetings last week, looking to revisit the agreement.

So the Twins swapped Welker, a reliever, for Johnson, 29. Johnson was 10-4 with a 2.39 ERA in 26 games, including 21 starts, for Class AAA Indianapolis last season. He walked 43 and struck out 94 in 135⅔ innings with a fastball ranging from 88-92 miles per hour. He also throws a slurve and a changeup.

"He ought to be able to compete for a spot on our ballclub," Ryan said. If not, Johnson could start the season at Rochester, providing depth to the rotation.

The Twins will release their 40-man roster Wednesday.