The 27-year-old Arrieta returns to the Cubs for the second time this season, as he made a spot start in game two of a doubleheader against the Milwaukee Brewers on July 30, allowing one run on two hits and three walks in 6.0 innings, fanning two in a no-decision. Arrieta was acquired by the Cubs from Baltimore as part of the deal that sent right-handed pitcher Scott Feldman to the Orioles on July 2. Outside of the one start with the Cubs, Arrieta has pitched for Iowa and gone 2-2 with a 3.56 ERA (12 ER/30.1 IP) in seven starts with Chicago's Triple-A affiliate.
Arrieta is 20-25 with a 5.39 ERA (218 ER/364.0 IP) in 70 major league appearances, all but six as a starting pitcher, in all or part of the last four seasons with Baltimore (2010-13) and the Cubs. He was originally selected by the Orioles in the fifth round of the 2007 Draft and made his major league debut in 2010 at the age of 24. He was a 10-game winner for the Orioles the next season in 2011, going 10-8 with a 5.05 ERA (67 ER/119.1 IP) in 22 starts. Arrieta has split the last two seasons (2012-13) between Baltimore and Triple-A Norfolk.
The 6-foot-4, 225-pound Arrieta was Baltimore's Opening Day starter in 2012 and a member of Baltimore's Opening Day roster this year. In 2013, he had had three stints with the Orioles, going 1-2 with a 7.23 ERA (19 ER/23.2 IP) in five starts. With Norfolk, Arrieta went 5-3 with a 4.41 ERA (24 ER/49.0 IP) in nine appearances (eight starts) this year.
Arrieta was drafted by the Orioles out of Texas Christian University and made his professional debut in 2008. A year later, he advanced as high as Triple-A, combining to go 11-11 with a 3.40 ERA (57 ER/150.2 IP) in 28 starts between Double-A Bowie and Norfolk. He began the 2010 campaign by going 6-2 with a 1.85 ERA (15 ER/73.0 IP) in 12 appearances (11 starts) with Norfolk to earn his first promotion to the big leagues.
Sanchez, 24, is 0-1 with a 5.68 ERA (4 ER/6.1 IP) in four relief appearances with the Cubs this season. He was claimed off waivers from the St. Louis Cardinals on May 21 and has combined to go 1-1 with one save and a 3.71 ERA (14 ER/34.0 IP) in 28 relief appearances between Triple-A Iowa and Memphis.