His since-deleted post included a photo taken from the television broadcast showing the Red Sox starter with what appears to be a green glob inside his black glove. Later, a video of Lester touching that area of his glove before gripping the ball also surfaced on social media.
Throughout the day Thursday, the green glob out-paced the Green Monster by far in the conversation before Game 2, eliciting a statement from Major League Baseball saying there was no conclusive evidence of Lester violating MLB rules, followed by assurances from the Cardinals that they considered the matter a "dead issue," and then Lester stepping forward with an explanation.
It was only rosin, Lester said -- the same stuff that is available behind every pitcher's mound in baseball.
"The rosin bag's back there for a reason, and I just so happen to put it in my glove," said the left-hander, who delivered 7 2/3 scoreless innings in Boston's 8-1 win. "That seems to be the best system for me that works. I'm going to continue to do it. That's really it."
Asked about the controversy, Lester said, "I think you can take it as something that bothers you or you can take it as a compliment. I felt like I had good stuff last night -- obviously, last night's really not a night you want to use Vaseline. You want a grip on the ball, not throwing it off the backstop. … I can stand here and tell you that I just use the rosin. It's all I've ever used and all I will use."
Even before Lester spoke, MLB senior vice president of public relations Pat Courtney issued a statement saying officials had viewed the online video and determined there was no cause for action.
His statement read, "We cannot draw any conclusions from this video. There were no complaints from the Cardinals, and the umpires never detected anything indicating a foreign substance throughout the game."
According to rule 8.02.4 in the Major League Baseball official rule book, "the pitcher shall not apply a foreign substance of any kind to the ball." A violation warrants an immediate ejection.
But rosin is widely accepted, both for pitchers gripping the baseball and hitters the bat. Because Lester "sweats like a pig," according to Red Sox manager John Farrell, he deposits some of the substance into his glove and swipes his fingers over it when necessary.
"The one thing that seemed very odd is that it shows up in a lime green color," Farrell said. "I don't know how that can happen."
Lester could not explain that either.
"I saw the picture and I don't know what that is," he said. "It looks like a giant booger, almost. I don't know how that came about, with the lighting, I don't know. Like I said, I saw the picture, I don't know how that is. It's rosin, I guess with sweat and licking your fingers and rubbing your fingers in there, it may turn a different color, I don't know. I don't pay attention to that stuff when I'm pitching."
But he and Farrell were adamant: It was rosin, and nothing else.
"Categorically, yeah," Farrell said. "That's what he's using."
The Cardinals wanted nothing to do with the controversy in the hours before Game 2, with GM John Mozeliak telling MLB.com, "We were unaware of this and feel it is a non-issue," and manager Mike Matheny saying, "If that's what [Lester] claims, then that's what it is. That's all there is to it."
"I have to tell you, I hate that our organization is involved at all," Matheny said during a session with the team's regular beat reporters. "As an organization, we do a nice job with our young players trying to teach them about social media and how to use it and how not to. We go to great lengths doing it, so it was pretty disappointing that one of our young kids was part of this.
"But, once again, my statement is it's not something we noticed [during the game]. There was not one guy who came into the dugout that said, 'That ball is running all over the plate and it's not normal.' At that point, our antenna is up. But he made good pitches. That's all there is to it."
For the umpires to have investigated Lester's glove during the game, Matheny or another Cardinal would have had to alerted them to the issue, said umpiring supervisor Bruce Froemming.
But no one did.
"There isn't a pitcher alive who uses rosin for anything other than to get a better grip on the ball," said MLB Network analyst Dan Plesac, a former Major League closer. "Not to make the ball move, not to sink. You're not cutting it. You're not throwing a spitball. It's been going on as long as baseball has been played when the temperatures get cold. There's nothing worse for a pitcher than when the feel of the ball is slippery. You have no idea where it's going.
"Listen, [Lester] is at a point in his career that the last thing he's going to try to do is cheat and try to doctor a ball. You'd be a moron, and he's not a moron. He's a good pitcher. He's not doing anything different than probably 95 percent of the pitchers, whether it's on your pants, your hat, your hair, somewhere you can go to get a sticky feeling on the ball."
This is not the first foreign substance issue to make headlines during a Cardinals World Series appearance. In the 2006 Fall Classic matchup between the Cardinals and Tigers, Detroit starting pitcher Kenny Rogers was determined to have a brown substance on the palm of his pitching hand. Rogers, who claimed it was dirt and rosin, washed it off after the first inning. Then-Cardinals manager Tony La Russa never pushed the umpires to take a closer look at the substance.
And it is not the first foreign substance issue to make headlines for the Red Sox this season. In early May, Clay Buchholz faced questions about a shiny patch on his left forearm that he periodically rubbed with his pitching fingers during a start against Toronto. Former Major Leaguer Jack Morris, working the Blue Jays broadcast, suggested Buchholz was throwing a spitball.
"To me, that's night and day difference [to the current issue with Lester]," Morris said Thursday at the Series, where he is working as an analyst for MLB.com. "With a spitter, the ball moves and you're controlling the flight of the ball. The whole idea with a tacky substance -- they let batters have pine tar on the bat handle to get a better grip. They let a pitcher have a rosin bag for the tackiness. All [Lester] is trying to do is get a grip on his breaking ball, and I look at it as a safety issue. If he doesn't have the grip, it could slip and he could drill someone.
"Here's how I look at this: If nobody cares over there [in the Cardinals dugout], then I don't care either."
Mozeliak said Melling had received instructions from a club official to delete his Tweet and expressed apologies for taking away from Lester's strong start.
"He could've had anything on that glove and it wouldn't have mattered," Mozeliak said. "We didn't play well. He shouldn't be scrutinized over that for a game in which he pitched as well as he did."
Lester shrugged it off.
"I guess it's a compliment," he said. "I know what I do day in and day out to prepare to pitch for big league games. I know not once I've cheated, won't cheat, and I'll continue to hold that as part of who I am."