Mark Melancon came to Boston with big expectations this spring. After posting a 2.78 ERA and 20 saves with the Astros in 2011, the Red Sox traded both Jed Lowrie and Kyle Weiland to Houston to bring the reliever to Boston, with the plan that Melancon would serve as the club’s primary set-up man. But the season didn’t start off as planned. In 4 games with the Red Sox, Melancon faced 18 batters, recording just 6 outs, and allowing 10 hits, 5 home runs, and 11 earned runs in the process. He was optioned to Triple-A Pawtucket on April 18.

That’s the bad news. The good news is that Melancon has been outstanding since arriving with the PawSox, seemingly regaining some of the confidence that appeared to be missing during his time with the Red Sox.

“He’s done a nice job,” said Pawtucket manager Arnie Beyeler. “He’s been working on his off-speed stuff, a backdoor cutter, locating his fastball well, and keeping the ball down in the zone.”

In 9 appearances with the PawSox, Melancon has yet to give up a run, while earning 2 saves and striking out an impressive 17 batters in 9.2 IP. He attributes his success to regaining an aggressive approach on the mound, while also mixing in his secondary pitches.

“It’s just about being aggressive,” said Melancon. “My attitude as I go out to the mound is being aggressive and getting after it. I have to keep throwing inside. I’ve also worked on my curveball, I’m throwing my changeup more. I just feel more comfortable overall”

Looking back, the 27-year-old right-hander believes that he strayed from that aggressive approach during his short stint with Boston earlier in the year.

“There’s so many times, especially when you’re in big games and big situations, where you try to slow the game down -- sometimes that can happen too much,” said Melancon. “I think that I was trying to just slow it down too much. That took away from my aggressiveness and the way I was going about things. I needed to just re-evaluate and use that energy and adrenaline in the right direction as opposed to trying to stop it.”

On Wednesday, Melancon was able to stay aggressive and work himself out of a jam in the 9th inning. Entering the game in the bottom of the 9th with the PawSox holding a 5-2 lead, he struck out the first two batters (former Sox farmhands Joe Thurston and Ray Chang), but then allowed consecutive singles which brought the tying run to the plate. After falling behind in the count 2-1, Melancon went back to his fastball and got the final batter of the game to line out to right field, taking home the save.

“He made a nice pitch (on third batter of inning), the guy hit a groundball that could have gone right to somebody but it went up through the middle. That’s baseball,” said Beyeler. “Then he just got in a situation where he missed with some off-speed stuff, and he had to come back with a fastball. In the end, he got the out.”

Having now been optioned to Pawtucket for over 20 days, Melancon will burn his final option year in 2012. However, that also means that Boston front office has the luxury of moving the right-hander back-and-forth between Boston and Pawtucket as often as it chooses this season. That being said, it must be difficult for Melancon not to think about when he’ll get the call back to Boston.

“I’m just taking the opportunity to learn and progress as much as I can while I’m down here. Hopefully, in the long-run that will help me more than anything else.”

As Melancon has less than two years of major league service time, he’s under Boston’s control through at least the 2015 season, and possibly through 2016 depending how long he remains in the minors this season. So the Red Sox front office has every incentive to think about the long-term with respect to if and when he’s ready to re-join the big club.

SoxProspects Senior Editor Matt Huegel contributed to this column.