On Thursday, Ortiz revealed to reporters what few had feared. Since the 2006 season, he's been playing with torn cartilage in his right knee. Did the injury sap the power from Papi's once-potent bat?
On Saturday night, Ortiz delivered an emphatic "no" to 36,830 thrilled Red Sox fans.
In the first inning, Ortiz took three quick balls from Toronto starter Dustin McGowan. On the ensuing 3-0 pitch, he hit a missile into the visitors' bullpen, scattering a half-dozen Blue Jays relievers.
Ortiz seemed to enjoy his slow trot around the bases. It was his first home run at Fenway Park since April 21 -- three months, 34 home games and 129 home at-bats ago.
"To tell you the truth," Ortiz said after the game, "it's not going to be 129 at-bats no more. I guarantee it."
The list of the top 30 home-field home-run hitters does not include Ortiz even after that triumphant blast. With his fourth shot at Fenway, he joined 20 players -- including Mike Napoli, Elijah Dukes and Josh Fields -- at 54th on that list, behind such non-standouts as Doug Mientkiewicz, Kelly Shoppach and Tadahito Iguchi.
Consider this: Between April 21 and Saturday's round-tripper, Alex Rodriguez hit 10 home runs at Yankee Stadium and 19 in all. Gary Sheffield hit 11 homers at Detroit's Comerica Park, more than half his total of 21.
On April 21, Oakland's Jack Cust was languishing in the Pacific Coast League for the San Diego Padres' Triple-A affiliate, the Portland Beavers. From Ortiz's last Fenway homer until Saturday, Cust had been traded, called up and inserted into the middle of the A's lineup, where he hit eight home-field home runs out of a total of 15.
A pair of Blue Jays, Alex Rios and Frank Thomas, amassed 15 home-field homers between April 21 and Saturday, and 28 in all.
But were Ortiz's troubles a direct result of knee pain? Was he breaking down before nightly sellout crowds?
The answer, Ortiz said, is complicated. He is sore, and when you're sore and derive much of your power from lower-body strength, "it doesn't help, because I can't put no pressure on it, you know what I mean?"
If Ortiz indeed began hurting after twisting his knee in batting practice at Yankee Stadium -- sometime in June 2006, he told reporters last week -- the pain did not prevent a career-best power season last year.
Ortiz's three best months, by slugging percentage, in 2006 were July, August and September, all after he says he hurt the knee. He hit 16 homers before that Yankees series, one during and 37 after.
Ortiz's problems in 2007 might have started with physical pain, but what happened next was mechanical, not physical.
"My whole swing changed," he said.
For several minutes after Saturday's game, Ortiz grasped for words to describe his frustrations. He's had problems all year, and just when he feels he's figured it out, his power stroke leaves him again.
"It's just a whole bunch of different things," he said, "kicking in and kicking out, kicking in and kicking out."
A couple of days ago, he said, Boston's first-year hitting coach, Dave Magadan, offered him new pointers, such as using his hands more. He applied them on Saturday. They worked.
"I'm just looking at [Magadan] like, 'Dude, you should've told me this like three months ago,' " Ortiz laughed.
Through his struggles, Ortiz maintained a career-high .318 batting average. He did hit eight home runs on the road between Fenway homers. His long ball off McGowan gave him a team-best 15 for the season, and launched him into the American League top 10.
"I wouldn't say he's in a slump or anything like that," utilityman Eric Hinske said.
"I don't think David has had a lack of power," said catcher Jason Varitek. "It's just [that] sometimes ... you don't get enough pitches to hit and drive. But his swing looks more like himself right now, and it's a good thing for us."
Another potential factor in Ortiz's comparatively low home-field power: Fenway Park is notoriously tough on left-handed home-run hitters. Pesky's Pole in right measures just 302 feet from home plate, but the wall extends sharply back, forming one of the most extreme power alleys in baseball. The short side of the bullpen in right field measures 380 feet from home. The long side, in right-center, is 420 feet away, farther than the deepest part of most big-league ballparks.
In fact, home-field home runs are down for the entire team. Several players have complained about Fenway's beastly weather this year, which has kept the ball from carrying.
These facts have not kept Ortiz from becoming one of the most feared power hitters in baseball, but they have likely affected him. He has always hit more home runs in visitors' ballparks, usually in fewer at-bats. Since he joined the Red Sox in 2003, Ortiz has hit 80 homers at home and 108 on the road.
Ortiz's second at-bat on Saturday was a dramatic illustration of this disparity. He connected on a 1-0 breaking ball from McGowan, sending a towering shot to right field. The ball dropped just in front of the wall and bounced into the stands for a ground-rule double. It had no chance of curling around Pesky's Pole.
He thought it was gone, right?
"I thought, 'I'm playing at Fenway,' " laughed Ortiz, who added, half-jokingly, that he spent "the whole offseason" lobbying to pull in the right-field fence.
Since the announcement of his injury on Thursday, Ortiz has gone 6-for-12 with two doubles and a homer. There have been no public plans to pursue surgery.
If he keeps swinging the way he did on Saturday night, Ortiz can prove that he doesn't need it.
Alex McPhillips is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.