Harvey had talked his way into pitching. Facing elimination, he was going to complete his 2-0 shutout and send the series back to Kansas City.
But what has happened since then is a bit of a puzzle, and it's one the Mets and Harvey have not been able to solve. Harvey didn't have his best fastball in the ninth inning of that eventual defeat, and he hasn't had his best fastball since then.
He's no longer hitting 97 mph on the radar gun, but now regularly dotting 94 and 95, and is thus much more hittable than he'd been in the past. Harvey has run off three straight awful starts, in which he has given up 16 earned runs in 13 1/3 innings.
The Mets have publicly pronounced that Harvey's issues are mechanical and not physical. But is it possible that some of his issues are in his head? Manager Terry Collins noted that Harvey looks like a different pitcher in the bullpen than when he's facing batters in games.
What is Harvey going through right now? He's not talking, leaving us to guess how he's doing. But multiple people, including former Mets TV analyst Bob Ojeda and Baseball Tonight's Dallas Braden, think he might be carrying some lingering guilt from being unable to complete the ninth inning of Game 5.
"And that's unfair, because [wanting the ball in the ninth inning is] what you would want in an ace," said Braden, who formerly pitched for the Athletics. "But now he's on the shakiest ground he's ever found himself on. He doesn't know who he is. He can't roll out the 'Dark Knight' persona. He's not throwing 100. He's throwing 94. He's flipping a coin trying to figure out who he is.
"The biggest question he's dealing with is: Is this permanent?"
The Mets don't provide media access to their mental skills coach, Will Lenzner, so it's hard to get a feel for how they (or his agent Scott Boras) are helping Harvey deal with the mental side of things. A look at Lenzner's Twitter and Facebook pages is interesting in that within the last 10 days, he has tweeted:
-- Referencing Andy Murray: "A mental block can hamper the success of even the most elite athletes. Once you gain the mental strength needed to succeed, it's important to maintain it." (with a link to an article about Andy Murray)
-- Regarding Kevin Durant: "The greats make everyone else fear what they might do and respect their ability to actually do it -- but they do it with results. Mental edge is everything!"
Collins spoke to Lenzner's role before Sunday's game.
"We have those people on staff here -- those mental-skills coaches that help you try to get through stressful situations," Collins said. "Our guy is very good. He's talked to Matt several times. But I do believe there still are the results. The best way to have some confidence is to go out and pitch good."
Two Mets minor leaguers provided examples on the approach taken by Lenzner's staff.
"The No. 1 thing we worked on together was establishing a highlight reel for me," one said. "So taking myself to those days that I was absolutely in the zone or my best outing sort of thing and essentially replaying that in my mind to get me in a positive state of mind.
"With pitchers they talk a lot about routine," said another. "From the time we wake up in the morning, stretching, and eventually getting ready to be in the game. Also, they incorporated breathing exercises such as a three-second inhale, three-second pause, and three-second exhale. There's also talk about how I (the pitcher) am in control even when it's a high-pressure situation."
What else might a mental-skills coach do to deal with the issue of a pitcher (though not necessarily Harvey) losing fastball velocity?
"I think there is a distinction between a younger pitcher or a pitcher in his prime losing velocity and a pitcher past his prime, or at least his fastball prime having the same problem," said Ray Karesky, who has worked for various teams in major league baseball for 32 years, including most recently with the Diamondbacks.
"With the younger pitcher losing velocity, it is more likely to be a problem with mechanics or maybe a nagging injury, possibly one he has not even acknowledged. Sometimes it stems from a lifestyle issue where the player is not taking good enough care of himself, such as getting enough sleep or following workout regimens."
The question becomes whether Harvey, now 27, still falls into the category of being younger or in his prime, given that he set a record last season for most innings logged in the first year back from Tommy John surgery.
"Players, and even staff at times, are often too quick to jump on mechanics as the key issue, since this is 'cleaner' and easier to acknowledge than some physical problems, lifestyle excesses or mental or psychological issues," Karesky said. "Adjusting mechanics when they are not really the problem only adds to the difficulty of getting the player back on track.
"With veterans, as well as younger pitchers, it is important to find out if something has happened in the player's personal life that has impacted his performance. This is something many or even most players do not easily acknowledge or worse actively resist talking about yet can subtly or dramatically impact velocity and other aspects of his game."
In other words, getting over the mental hump of this slump takes a lot of work from all involved. The puzzle has a lot of pieces that need to be fully examined.