With David Pauley being sent back to Triple-A Pawtucket after filling in for Josh Beckett (flu and stiff neck) on Tuesday, the Sox called up Hansen to take Pauley's spot on the roster.
The fact that reliever Manny Delcarmen has also been sidetracked by the flu the past couple of days made Hansen a logical choice.
And the right-hander was thrown right into the fire. With Daisuke Matsuzaka scratched shortly before game-time and Jon Lester thrust into the start on three days' rest, manager Terry Francona had to go to his bullpen in the sixth inning.
The man he went to was Hansen -- this in a game that was locked in a 4-4 tie. Hansen retired the first two batters, but then surrendered a solo shot to Casey Kotchman that wound up being the difference in the game.
In general, however, the Red Sox were encouraged by the way Hansen (1 2/3 innings, two hits, one run, three strikeouts) pitched. And the fact he was the losing pitcher had nothing to do with why he was sent right back down to Pawtucket after the game.
With Lester no longer able to start on Thursday, another roster move was necessitated so that Justin Masterson can come up from Double-A Portland and pitch the series finale vs. the Angels. In other words, good-bye, Hansen. But perhaps not for long.
"I thought he threw the ball great," said Francona. "He left one pitch up, and Kotchman didn't miss it. He was throwing with confidence, aggression and throwing his slider 88-89 mph with some bite to it. He pitched with no fear. I thought he did very well."
Hansen handled the topsy-turvy day in a professional manner.
"I felt pretty strong out there," Hansen said. "I felt like my pitches were working. There was one or two pitches that I guided and, obviously, [the home run] was a mistake, and it was hit a long way."
Even if it was just for a day, Hansen loved being back in Boston for the first time since '06.
"It felt like I had my debut all over again," said Hansen. "It was great to go back out there, great to be back in Boston for a day at least. I enjoyed every minute of it."
After signing a Major League contract with the Red Sox just months after the 2005 First-Year Player Draft, Hansen has had a tough time staying consistent. But he feels as if he's made a big leap since the second half of last season.
The numbers have backed that up, as Hansen hasn't allowed a run in his first eight appearances for Triple-A Pawtucket.
"I'm just basically working on my routine, staying consistent, doing the things I need to do in order to get better," said Hansen.
Hansen is starting to regain the swagger he had when he was a dominant closer at St. John's.
"I feel like I'm a totally different pitcher from when I first came up, but I feel the same as I did in college," said Hansen. "Maybe that's a good thing. I hope it is. It's the same mechanics [as college]. I noticed it last year during the All-Star break. I went home and saw pictures that my mom had up and was able to build off of that and see what the differences were.
"So after that, I went back to my old mechanics and decided to see where that would take me. I wasn't having a great first half, so I decided I'd try anything, so it's been working. I'm staying consistent with it, and that's what I'm happy with."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.