Buchholz allowed three hits over five innings in his first start since early June and the AL East-leading Red Sox beat the Tampa Bay Rays 2-0 on Tuesday night.
"A healthy Clay Buchholz is going to be a great addition," Farrell said. "He showed it tonight. To see him walk to the mound, I think it gave everybody a boost in confidence."
Buchholz (10-0), sidelined by a strained neck, hadn't pitched in the majors since beating the Los Angeles Angels on June 8.
"He looked great ... looked like he hadn't missed a day," Boston catcher Jarrod Saltalamacchia said. "To be able to go into a game like this after not pitching in a big league game for that long, keep your poise and just make it look like it's any other game, it's tough to do."
Buchholz, who made three rehab starts in the minors, struck out Jose Molina with two on to end the second. He admitted that he was anxious before the game
"It felt pretty good," Buchholz said. "A long time coming for me, so I'm definitely happy to be back out there."
Jonny Gomes and Saltalamacchia both drove in a run for the Red Sox, who extended their lead over second-place Tampa Bay to 8½ games in the East. Craig Breslow, Junichi Tazawa and Koji Uehara finished a four-hitter. Uehara got the final four outs for his 19th save.
Reigning AL Cy Young Award winner David Price (8-8) lost his third straight start despite giving up just two runs and three hits in eight innings. The left-hander struck out nine.
The Rays, 4-12 since August 25, are leading the race for the second AL wild-card spot.
"You can't dwell on it," Price said. "We've got 19 games left, so you go now or we won't be hanging around in October."
"It's a play that should be made," Jennings said.
Gomes followed with a single that drove in Napoli to put the Red Sox up 1-0.
Gomes, who has 15 RBI over his last 17 games, scored to make it 2-0 later in the fifth on a sacrifice fly by Saltalamacchia that required a leaping catch near the wall by Jennings.
Saltalamacchia threw out a runner attempting to steal second in both the third and fourth innings.
Uehara replaced Tazawa after Yunel Escobar hit a two-out double in the eighth. The Red Sox closer ended the threat by getting a foul popup from Wil Myers. The right-hander has retired the last 31 batters he has faced.
"Unbelievable," Buchholz said. "It's the only word I can use to describe him."
The announced crowd was 18,605. Tampa Bay started the day with the majors lowest home attendance average at 18,719. ... Boston 2B Dustin Pedroia hit leadoff for the first time this season and singled in four at-bats. Farrell didn't rule out Pedroia staying in the role until OF Jacoby Ellsbury returns from a foot injury. ... Ellsbury missed his fourth consecutive game and will not resume baseball activites for at least the next few days. ... Tampa Bay reliever Jesse Crain (strained right shoulder) had his second bullpen session and could throw batting practice within the next week. ...The Red Sox reinstated Buchholz from the 60-day disabled list and designated RHP Jose De La Torre for assignment.