It was after singles by Rajai Davis and Anthony Gose put runners at the corners with one out that Valentine came out to talk to Buchholz.
"I thought he was coming out to get me," said Buchholz. "He was like, 'I was just coming to check on how you were doing.' I was like, 'Go back to the dugout and let me try to get a ground-ball double play right here.' The guy took second, I ended up walking him, and I gave up the run."
The crowd cheered as the righty stayed in the game. Following a steal of second by Gose, Buchholz intentionally walked pinch-hitter Kelly Johnson.
That put the game in the hands of Omar Vizquel, and the 45-year-old delivered with a sacrifice fly to medium-depth left field, snapping a 3-3 tie.
In a show of sentimentality, Blue Jays manager John Farrell gave Vizquel the start at second base, knowing it would be the last time he had a chance to play at Fenway Park.
"That's very nice for him to give me the chance to play here my last time," said Vizquel. "I'm glad that things went all right. My last at-bat was a good at-bat, game-winning RBI and I feel pretty special, because I have a lot of memorable moments here."
Despite the result, there was no reason for Valentine to second-guess his decision to stick with his starter.
"He made good pitches the whole night -- he deserved better," said Valentine. "He got a little blooper to left with two strikes. He did pretty good."
Twice in the bottom of the ninth, the Red Sox nearly won the game with one swing.
After a leadoff single by James Loney, Cody Ross drilled one down the line in left that had plenty of distance. But before you could say "Carlton Fisk," the ball hooked just foul.
"Man, I thought for a second that I had it, but it just seemed like it took a left turn and unfortunately it went foul," said Ross.
Up stepped Jacoby Ellsbury, who had already hit a home run earlier in the game. This time, he belted a first-pitch fastball by Casey Janssen to straightaway center. For a second, it provided a memory of when Ellsbury hit a ball in the exact same direction for a walk-off homer against the Indians last August.
This time, the ball died at the warning track, and Colby Rasmus camped under it for the out.
"As soon as I came in to the dugout, I was watching Jacoby and he hit it and I got excited for a second and just saw Rasmus kind of drift back on it," said Ross. "We put a couple of good charges into it, but we weren't able to get it done."
Such is life these days for the Red Sox, who have lost four in a row and 11 of 12 to fall to 63-78 on the season. This is the first time Boston has been 15 games under .500 since the end of the 1992 season.
"It's been a long time since this team has been in this position, so we've got to grind through it and put some good at-bats together like the guys did today," said Buchholz.
Buchholz went 8 2/3 innings, giving up seven hits and four runs.
Trailing by a run in the sixth, Dustin Pedroia delivered an equalizer for the Red Sox, a solo shot that soared over the Green Monster.
"Clay pitched outstanding," Ross said. "They had a couple of hits and runs where it worked out, and they scored a couple of runs on it. It was unfortunate, because he just threw so well and we weren't able to get that run home for him."
The Red Sox did something that has been all too infrequent in recent weeks as they jumped out to an early lead. After Ross drew a one-out walk in the second, Ellsbury hammered a two-run homer into Boston's bullpen in right-center.
Buchholz held the Jays scoreless over the first three innings, but he ran into a jam in the fourth. Davis and Gose started the rally with one-out singles. Jeff Mathis ripped an RBI single to right. Vizquel's sacrifice fly to left tied the game at 2. Adeiny Hechavarria put Toronto ahead with an RBI single to left.
"If we don't create anything -- that ground ball that Mathis hits, that's a ground-ball double play and he's out of the inning," said Farrell. "[Buchholz has] been very efficient for a better part of two or three months. He's got an outstanding changeup that he used a lot today, and he was efficient. He's a damn good pitcher."