Lincecum went 2-6 with a 9.16 ERA in nine starts for the Angels and served up 11 homers in 38 1/3 innings. Opposing hitters batted .395 against him as he gave up 68 hits and walked 23 for a horrid 2.37 WHIP.
The 32-year-old right-hander was roughed up for six runs and nine hits in 3 1/3 innings in a loss to the Seattle Mariners on Friday. Lincecum pitched five or fewer innings in seven of his nine outings.
"He hasn't progressed from his first couple starts," Angels manager Mike Scioscia told reporters on Saturday. "He's regressed."
The Angels have 10 days to decide whether to trade, release or send Lincecum to the minors.
Lincecum has a 110-89 career mark with a 3.74 ERA in 10 major-league seasons, the first nine with the San Francisco Giants.
Lincecum won the National League Cy Young Award in consecutive seasons in 2008 and 2009. He went 18-5 with a 2.62 ERA in 2008 and 15-7 with a 2.48 ERA the following year.
In an 11-month span between July 2013 and June 2014, Lincecum pitched two no-hitters. He has been an All-Star four times and helped the Giants win World Series titles three times in five years.
Lincecum underwent season-ending hip surgery last season and was trying to revive his career with the Angels. He signed with the team on May 20 and made his Angels debut on June 18 when he gave up one run and four hits in six innings while beating the Oakland Athletics.
Los Angeles recalled right-hander Jose Valdez from Triple-A Salt Lake to fill the roster spot.