PAWTUCKET — About the only thing that went right for the Pawtucket Red Sox last night was the most important of all.

Mike Timlin looked good in his best rehab performance yet, but the PawSox struggled to a 5-2 loss to the Columbus Clippers. Timlin pitched a perfect 1-2-3 inning and pronounced himself ready to return to the bullpen in Boston. No word on Timlin’s status for this weekend’s series against the New York Yankees is expected until today.

“I felt like I was ready a long time ago but obviously I wasn’t. That’s irrelevant, what I feel,” Timlin said. “It was a good outing. I threw 80 percent strikes, which was good.”

The night started off on a poor note when expected starting pitcher Runelvys Hernandez reported to work yesterday and decided to exercise an option to vacant his contract with the Red Sox organization. Hernandez had until today (June 1) to choose to stay in the system or become a free agent.

“It’s a reminder that this is a business,” said manager Ron Johnson. “We weren’t caught off-guard, necessarily. We knew this was an option and this is a level where stuff like that happens.”

Johnson tabbed Abe Alvarez to fill the spot in the rotation and it wasn’t a good night for the lefty. Alvarez, who pitched two innings in relief on Sunday, was roughed up for five runs over 4 1/3 innings and dug a hole his weak-hitting teammates couldn’t battle out of. Felix Diaz, a veteran righty who’s pitched in the majors for the White Sox, stifled the PawSox for seven innings and left the game with a 5-0 lead. He picked up the win and is now 4-4 on the year.

Alvarez, who fell to 3-4, allowed three singles, a double and a walk in a busy fourth inning. Brandon Harper hit a two-run double to give Columbus a 2-0 lead and then a wild pitch allowed a third run to score. With the bases loaded and two out, Brandon Watson laid down a perfect bunt that let Harper breeze in with the Clipper’s fourth run.

Columbus added a fifth run in the fifth inning when Kory Castro hit a solo home run. That ended Alvarez’s night and brought Pawtucket’s relief corps into action. That was clearly the home team’s bright spot.

First Manny Delcarmen didn’t allow a hit and struck out three of the five hitters he faced in relief of Alvarez.

Timlin took over for the start of the seventh inning and also breezed. He threw just 12 pitches, eight for strikes, in setting the Clippers down in order. He retired Watson on a grounder to first base, got Bernie Castro to pop up to short left field and watched Darnell McDonald hit a lazy fly ball to center.

Craig Breslow replaced Timlin and also pitched well, allowing just one hit over an easy eighth and ninth innings.

The Pawtucket offense continues to struggle. The Sox are last in the International in runs scored (194) and came into last night hitting .246 as a team, tied for second-to-last. They managed only five hits last night and never mounted a rally off of Diaz.

The same couldn’t be said for the Clippers’ first reliever, Alex Morales. He opened the eighth inning by walking the first two hitters and allowing a Joe McEwing single to load the bases. David Murphy then hit a long, loud fly ball that wasn’t chased down until McDonald’s back was up against the right-field fence.

“I thought it was gone off the bat. When he hit it, I thought that was a [grand] slam right there,” said Johnson.

The long out drove in Chad Spann with the PawSox’ first run and a walk to Brandon Moss to load the bases again ended Morales’ ugly stint on the mound. Closer Chris Booker came in and walked Michael Tucker to force in Jacoby Ellsbury with the second run of the inning, but Booker escaped further trouble in the eighth and pitched a perfect ninth to close out the Sox.

Timlin was happy with his one inning of work which came under the watchful eye of Boston manager Terry Francona and pitching coach John Farrell.

“Not too bad,” Timlin said. “It was time on the mound. That’s all it was. Just getting a feel of a release point.”

Asked if he could throw for the Red Sox at Fenway this weekend, Timlin answered, “I don’t expect things anymore. It’s not my decision.”

kmcnamar@projo.com