Welker made his big league debut this season with the Bucs, tossing 1 1/3 hitless innings in a pair of late-June appearances. The 27-year-old, signed as a second-round pick in the 2007 First-Year Player Draft, posted a 3.57 ERA in 48 appearances, including nine saves, with Triple-A Indianapolis.
Morneau batted .260 with three RBIs in 25 September games with the Bucs and is 4-for-13 in the first three games of the postseason.
Presley spent significant parts of each of the last four seasons with the Pirates and batted .283 in 28 games with the Twins following the trade.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. Thomas Harding is a reporter for MLB.com. Follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.