The San Diego Padres have announced they acquired right-handed pitcher Erik Johnson and infielder Fernando Tatis Jr. from the Chicago White Sox in exchange for right-handed pitcher James Shields and cash considerations.  Executive vice president/general manager A.J. Preller made the announcement.
 Johnson, 26, has made two starts for the White Sox this season, while also making eight starts for Triple-A Charlotte where he has gone 2-1 with a 2.94 ERA (16 ER, 49.0 IP) and 35 strikeouts against 17 walks.  The right-hander was originally signed by the White Sox as a second-round selection out of the University of California, Berkeley in the 2011 First-Year Player Draft. He made his Major League debut for Chicago in 2013 and has gone 7-6 with a 4.50 ERA (49 ER, 98.0 IP) and 77 strikeouts against 49 walks over 18 Major League starts across parts of four Major League seasons (2013-16) for the White Sox. Over parts of six minor league seasons in the White Sox organization (2011-16) he has gone 36-24 with a 3.23 ERA (188 ER, 523.2 IP) and 454 strikeouts against 182 walks in 94 games, 91 starts. 
Tatis Jr., 17, was signed by the White Sox as an international free agent on July 2, 2015 out of the Dominican Republic.  The right-handed hitting infielder is the son of former Major League infielder Fernando Tatis, who enjoyed an 11-year Major League playing career with the Texas Rangers (1997-98), St. Louis Cardinals (1998-2000), Montreal Expos (2001-03), Baltimore Orioles (2006) and New York Mets (2008-10). Tatis Jr. has yet to make his professional playing debut.
Shields, 34, has gone 2-7 with a 4.28 ERA (32 ER, 67.1 IP) and 57 strikeouts against 27 walks in 11 starts for the Padres this season. The right-hander made his Padres debut last year by going 13-7 with a 3.91 ERA (88 ER, 202.1 IP) over 33 starts in 2015.
He signed with the Padres as a Major League free agent in February 2015, to a four-year contract through the 2018 season with a club option for 2019. Over parts of 11 Major League seasons with Tampa Bay (2006-12), Kansas City Royals (2013-14) and Padres (2015-16), he has gone 129-104 with a 3.76 ERA (910 ER, 2180.0 IP) and 1,899 strikeouts against 560 walks in 330 games, 329 starts.