"It was spectacular," said manager Bobby Valentine. "Clay came out and had all of his pitches right from the get-go. I thought his changeup and the arm speed on his changeup was spectacular."
Boston avoided a sweep at the hands of its division rivals and improved to 3-6 against Baltimore this season. The Sox open a three-game series vs. the Nationals on Friday as they wrap up a six-game homestand.
All of Buchholz's shutouts have come vs. the Orioles, including a no-hitter in his second Major League game on Sept. 1, 2007.
But more impressive for the right-hander are his last three outings, which have lowered his ERA from 7.84 to 5.77. Buchholz recently made an adjustment on his changeup and has since allowed four runs in his last 24 innings, while striking out 19.
"The only adjustment was the grip. I think my grip was a little off," Buchholz said. "I've been able to free that up a little bit. It's been a pitch that we tried to work on for a lot of the time and noticed it wasn't the grip I had the past couple years and it's coming back."
Buchholz allowed just one baserunner to reach scoring position and induced three double plays.
After failing to give Josh Beckett adequate run support in Wednesday's 2-1 loss, the Red Sox loaded the bases in the first two innings and scored two runs in each of the first three frames.
Adrian Gonzalez emerged from a 2-for-17 skid with a two-run double in the first to score Dustin Pedroia and Kevin Youkilis. Gonzalez finished the game 3-for-4.
"With the bases loaded it was big for us to get ahead in the game, and Buchholz took care of the rest," Gonzalez said.
In the second, a throwing error by Robert Andino allowed Kelly Shoppach to score after Pedroia drove in Darnell McDonald with a grounder to second.
The Sox chased Orioles starter Brian Matusz in the third after Gonzalez's second hit of the night. Matusz allowed five runs (four earned) on four hits over two-plus innings. He walked five and threw 67 pitches.
Reliever Miguel Gonzalez entered and promptly surrendered a two-run single to Daniel Nava to push the lead to 6-0.
It was the offensive start the Red Sox knew they would need Thursday after being shut down by the Orioles' pitching staff the previous night.
"Early leads are always good for the pitchers," Gonzalez said. "If you get an early lead to a starter, they can get into a groove and work on getting ahead of hitters. Buchholz did an unbelievable job and it was nice to get the runs for him. It would have been nice to be able to do it for Josh, because he threw a heck of a game yesterday."
Nava reached base four times and had two hits with a run scored. It was just another solid game for the left fielder who has reached safely in 14 of 25 plate appearances this month.
"It was such a complete game today," Valentine said of Nava's performance. "He walked, he hit, broke up double plays, made that catch against the wall. It was absolutely a complete game tonight."
Nava hit leadoff for the fifth time this year and the seventh time in his career. Boston is 7-0 in those games.
"It feels good to get on base for the guys behind me," Nava said. "The guys behind me obviously can do some damage. I think if that's my job to get on base at the top of the lineup, I'm happy to do it. If it's in the nine-hole, so be it."
The Red Sox avoided dipping below .500 for first time since they were 23-24 on May 27.
"We needed that win, especially here against Baltimore here at home to get back on the winning track," Gonzalez said.