Robertson delivered the first walk-off grand slam in Rays history, and it capped a five-run ninth. The five runs allowed are a career-high for Barraclough, who also logged a career-high 40 pitches in the frame that spun away from him.
"Working behind in counts the whole time," the Miami closer said. "It's hard to get back into counts when you're working [from] behind. They're good fastball hitters, so when you work behind and get in bad counts, they're sitting dead red and hitting fastballs. What are you going to do?"
Robertson's grand slam came on a 1-0 pitch, following a two-out walk to Willy Adames to load the bases.
A subject of trade rumors, Barraclough has been one of the top relievers in the National League this season. He had allowed two runs in an outing just once, against the Mets on April 10.
"Up until that ninth, obviously, everything went well for us," Marlins manager Don Mattingly said. "It just doesn't go good in the ninth."
The Tampa Bay comeback denied the Marlins of their first series sweep of the season, and snapped their season-high four-game winning streak.
Until the late rally, the story of the afternoon for the Marlins was Richards, who was in control over 6 2/3 innings, allowing one run.
With Richards, there's nothing flashy. What you see often is what you get, which is usually composure, no matter how his day on the mound is going. On an afternoon when Rays right-hander Chris Archer struck out 13 amid speculation he soon may be traded, Richards was steady and unflappable over his 102-pitch performance.
Archer was flashy, triggering the radar readings of his fastball as high as 97.2 mph. The Rays right-hander complemented his 40 four-seam fastballs with 51 sliders.
Richards' four-seam fastball averaged 90.3 mph, and it topped at 91.6 mph. But he kept Tampa Bay off stride by mixing in 34 changeups -- inducing nine swinging strikes.
"I just tried to not worry about what [the Rays] were doing," Richards said. "Just focus on myself and keep attacking the zones and mixing speeds on them. I would have liked to have attacked the zone a little more with my fastball. I got behind in some counts I shouldn't have, but I was able to get out of it with my changeup."
MOMENTS THAT MATTERED In terms of the big picture, Richards getting into the seventh inning for the second time in his career was significant, because the rookie is still establishing himself. In the seventh, the right-hander logged two quick outs, before Mallex Smith tripled. Richards was lifted and Brad Ziegler entered, and the reliever struck out Adames, preserving a three-run Miami lead.
"There was a lot of good stuff," Mattingly said. "That's what's disappointing. Trevor was good today. Zieg does his job. We score early off Archer, and then he shuts us down. We had a couple of chances to add on, but we weren't able to."
SOUND SMART Miguel Rojas' two-run double in the second inning extended his career-high road hitting streak to 11 straight games. He is hitting .447 in those games.
HE SAID IT "I thought he was still OK. [It was going to be] his last hitter. It ended up being his last hitter, but we knew at that point. We ended up giving him a chance to get out of it right there." -- Mattingly, on sticking with Barraclough for 40 pitches while Javy Guerra was ready
GETTING TOSSED Cameron Maybin's day was over in the fourth inning after the Marlins center fielder was ejected by home-plate umpire Andy Fletcher for contesting being called out on strikes, using choice words while walking back to the dugout. Yadiel Rivera replaced Maybin in center field. It was the third time in his career that Maybin has been ejected, with the other two coming in 2016.
Maybin said he had some issues earlier in the season with Fletcher's strike zone. And the veteran outfielder said he was inquiring about pitches earlier in the count, which is common for players to gauge where the zone is being called.
"The first slider wasn't close," Maybin said. "Usually players can ask an umpire, 'Hey, was that as far out as you're going? Is that top or bottom?' I just was asking him so I know if I need to protect that pitch."
UP NEXT The Marlins open a two-game set vs. the Braves at Marlins Park on Monday at 7:10 p.m. ET. Starter Jose Urena is 0-2 with a 5.25 ERA in 12 innings this year against Atlanta, and he's winless in seven decisions at home this year. Lefty Sean Newcomb gets the nod for the Braves.