Shoemaker hasn't pitched since the Angels' 7-5 win over the New York Yankees on June 14. He went three innings, allowing four earned runs on six hits before making way for Parker Bridwell.
The expected timetable for Shoemaker's return means the 30-year-old right-hander will almost certainly miss the remainder of the 2017 season. He has made 14 starts this year, going 6-3 and posting a 4.52 ERA and a 5.11 FIP, per Baseball Reference.
While the Angels have been without Shoemaker for over a month, the fact he's now out for the year is undoubtedly a blow to a team that's just three games back of the Kansas City Royals for the final wild-card spot in the American League.
The Orange County Register's Jeff Fletcher reported Shoemaker's forearm issue isn't expected to linger into next year, so the Angels should at least expect him to be back to his best in 2018.