Arrieta spent four-and-a-half seasons as a member of the division-rival Chicago Cubs before becoming a free agent this offseason. The 31-year-old is coming off his worst season with the Cubs, with a 3.53 ERA and 4.16 FIP over 30 starts.
The Brewers' starting rotation ranked eighth in MLB by FanGraphs' WAR, with the 10th-best ERA, despite the club having the league's lowest payroll. Heading into the 2018 campaign, it has an estimated payroll of $65.4 million, including arbitration projections.
Brewers ace Jimmy Nelson spent the end of September on the disabled list after tearing his labrum while sliding back to first base as a runner. Surgery is expected to sideline the 28-year-old right-hander for the beginning of the 2018 season, and the Brewers are actively looking for rotation help in his absence, according to Morosi.
Over 175 1/3 innings, Nelson posted a 3.49 ERA and 3.05 FIP, while Milwaukee missed the postseason by one win.