Giles, who hasn't allowed a run since June 18, has been bamboozling opponents recently. He's notched two or more strikeouts in nine of his last 10 setup appearances and held opposing batters to a .130 batting average in his last 14 games.
"Ken is as confident as he's been as an Astro," Hinch said.
In need of a power arm in the bullpen, the Astros sent five players to the Phillies last December to get Giles, who was Houston's biggest offseason acquisition.
"It's a comfort thing," Giles said. "New team, new environment. I just had to settle in a little bit. Sometimes when you're uncomfortable, you try to do too much, and I think that's what happened to me."
Giles was originally the front-runner for the closer job, but struggles in the spring led to the job going to Luke Gregerson and, eventually, All-Star Will Harris, while Giles worked mostly in the seventh and eighth innings.
"I think going down for a lesser role probably helped me out in the long run," Giles said.
The promotion for Giles means somewhat of a demotion for Harris. Since starting the season 9-for-9 in save opportunities, Harris has blown saves in three of his last five tries, including two of his last three games.
"[Harris] was understandably disappointed in his performance," Hinch said. "He's given up runs in a single-digit number of games this year, and they've come in bunches. That seems to be a norm of his in his career. He's had a little bit of trouble with that."
For a good portion of the season's first half, Hinch refused to name a closer, but Harris' sterling early play forced his hand. At one point, Harris went a club-record 37 consecutive games without allowing an extra-base hit, and allowed a run in only three of his 37 appearances.
But less than two months after getting his ERA down to a season-low 0.33 on June 8, Harris saw his ERA increase to 2.08, the highest its been since early April. Harris has allowed seven runs in his last 5 2/3 innings and was a major reason why Monday night's game went to 14 innings before the Astros prevailed.
"I think because he's been so dominant in the first few months, all of a sudden, giving up runs in a few games in a row gives the feeling that the sky is falling and something's wrong with him," Hinch said. "The reality is, it's the execution of a couple pitches that's gotten him burnt."
That said, Hinch did say he would be willing to use Giles earlier if the situation demanded it.
"I want to make sure we don't just put him down there in the ninth inning and only pitch him in saves, because I think it's important that he comes in and continues to get big outs," Hinch said. "But there aren't more people who are walking off the mound at the end of innings with more confidence than Ken."
Fantasy spin | Fred Zinkie (@FredZinkieMLB) Harris has struggled since being named to the American League All-Star team, posting an 11.12 ERA with three blown saves since July 8. The hard-throwing Giles, meanwhile, has a lifetime 12.2 K/9 rate and has the skills to be an elite closer for the duration of the season. In leagues in which Giles is unavailable, owners can consider adding new saves sources in Milwaukee (Tyler Thornburg), Seattle (Edwin Diaz) and Arizona (Jake Barrett).
Jordan Ray is a reporter for MLB.com based in Houston.