Barajas, the Pirates' catcher, crossed himself up on that fateful pitch. For a team that daily depends on perfect execution for a chance at victory, that blip was enough to make the difference between a lost Interleague Series and what would've been the Pirates' first victorious three-city road trip in seven years.
"We're playing without a safety net almost every game," manager Clint Hurdle said. "The ball getting away from Rod put us in a jam. It changed the whole dynamic of that inning."
Avila's game-winner might have been a cinch double-play ball in an infield playing at normal depth, where the Pirates would have been had Barajas' mistake not advanced Delmon Young and Jhonny Peralta to third and second, respectively.
"I [messed] that up," said Barajas, who had just switched his signs, wary of Young's presence on second. "I always have little keys to look for, like if the guy at second is staring at me I assume he's trying to figure something out. So I switched up the signs. Tony threw the pitch I called for. But I went with the old sign."
Watson threw a fastball. Barajas thought he'd called for the slider.
"Out of his hand, I expected the ball to go down in the zone," Barajas said. "It didn't."
Instead, it went off Barajas' mitt 25 feet to the left of home. The runners advanced and came home when Avila's slow bouncer snaked under Watson's glove, into center and through the Pirates' hearts.
"It makes up for some of the hard-hit balls right at guys," Avila said. "Squeezing one through there and getting a big hit. We've wasted a lot of good performances this year so far, so I'm glad we didn't waste that one."
It got the biggest piece of Kevin Correia's heart. Standing tall in Scherzer's considerable shadow, Correia took a two-hitter and a 2-1 lead -- courtesy of solo homers by Barajas and Neil Walker -- into the seventh.
Within his next six pitches, the Tigers doubled their hit total. Prince Fielder got a "leg" double, his blooper into short left caroming into foul territory off shortstop Clint Barmes' leg, and scored on Young's single.
"Tough game to lose," Hurdle said. "[Correia] goes out for the seventh with 74 pitches, Prince hits a ball off the end of the bat, the ball gets kicked -- just an unlucky play -- ground-ball single, and there you go."
For the Bucs, it was an extraordinary defeat beyond the submission to Scherzer, whose strikeouts were the most by an individual against Pittsburgh since San Francisco's Tim Lincecum also punched out 15 on July 27, 2009.
The loss was Pittsburgh's first this season in 14 games when leading after six innings.
Detroit's comeback was just in time to reward Scherzer, whose 15 strikeouts were the most for a Detroit pitcher since left-hander Mickey Lolich also logged 15 against the Boston Red Sox on Oct. 2, 1972.
"I've seen this guy pitch quite a bit," Hurdle, the former Colorado manager, said of Scherzer, the former D-backs righty, "and he's got a big arm. When he gets his breaking ball in play like today, he's tough. Matching someone like Lolich ... that's good stuff."
Scherzer's previous start was a four-inning shellacking (eight hits, six runs) by the White Sox, set up by a 37-pitch first inning. In this one, he didn't cross the 37-pitch mark until working to the third batter in the third inning.
Barajas first interrupted Scherzer's strikeout parade with a solo homer with one out in the fifth. Then Walker turned on a full-count offering with one away in the sixth and deposited it 408 feet away among the seats in straightaway right.
Walker's second home run of the season put the Bucs back on top, 2-1, after Peralta's homer in the bottom of the fifth had knotted the game at 1.
Minus those brief lulls, Correia was receiving regular reminders that his lot hadn't changed: He still had to suck it up against a dialed-in foe, just as he did against Josh Johnson and Stephen Strasburg before him, and Johnny Cueto before him, and Clayton Kershaw before him.
"He's had some tough draws," Hurdle had to concede. "And he had another one today."
Correia was the picture of a conflicted pitcher afterward. He had rebounded assertively from his previous start in Miami, where the Marlins had knocked him around for six runs in less than four innings. But all it had gotten him was a loss, his fifth in six decisions.
"I've pitched against some really good pitchers this season," he said, "and when they're on their best, as the guy today obviously was, there's no room for error. That was probably the best I've felt since my first few starts. They have a tough offense and I threw it as good as I've thrown this season."
Barajas added a sacrifice fly in the ninth inning to account for the final margin.