With an upcoming off-day Monday, the Giants won't need a fifth starter until Sept. 5 at Milwaukee, and Giants manager Bruce Bochy said he's "leaning" toward waiting until then to use that spot in the rotation again.
"Alex will help us in the 'pen," Bochy said before the series opener against Colorado. "He gives us another left-hander, and we've been using the 'pen quite a bit. The new addition, especially being left-handed, is going to help."
Martinez has to spend 10 days in the Minor Leagues before he's eligible to be recalled, so he won't be an option to start that Sept. 5 game.
Martinez has been roughed up in his past two starts. In an 11-0 loss Thursday night to Arizona, he gave up eight earned runs on 10 hits. Martinez allowed nine hits and five earned runs in his previous start against Colorado. For the season, he's 3-2 with a 7.52 ERA.
Martinez spent 104 games on the disabled list earlier this season after being drilled in the head by a line drive April 9 against Milwaukee.
Hinshaw made the Giants' Opening Day roster but was sent down after posting an 8.44 ERA in seven relief appearances. In 46 relief appearances for the Grizzlies, he went 1-2 with a 3.96 ERA and one save with 72 strikeouts and just 32 walks. He held opposing batters to a .212 average.
Bochy said he expects Hinshaw to help primarily in the middle innings.
"I had a couple mechanical flaws I had to work out," Hinshaw said. "Once I started to get my groove back, they started putting me in closer game situations, setup relief, closing a couple days when the closer was down. Just did whatever.
"I just want to come in here and contribute in whatever role they put me in, just come in and keep games close, maybe put out some fires."
Eric Gilmore is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.