ST. PETERSBURG -- Maybe it’s fitting that the Mariners’ most trying road trip of the season has arrived during this weave through Florida. Because in these parts, when it rains, it pours.

Seattle suffered another gut-punch loss on Tuesday night at Tropicana Field, when the Rays capitalized on two walks that ended Luis Castillo’s night in the sixth inning and gave them momentum towards a tiebreaking four-spot that sunk the Mariners to an 11-3 defeat.

Mike Baumann was on the mound for those four runs, pitching for the third day in a row, then Eduard Bazardo and Cody Bolton coughed up five more runs (three earned) in the seventh and eighth. Bazardo also walked two to bring Seattle’s free pass total to six, one shy of a season high.

The club has now lost six of eight so far on this road trip, falling to 18-25 overall away from T-Mobile Park, and will look to avoid being swept for the first time all season in Wednesday’s finale, after which it returns home.

Since winning the trip’s first game last Tuesday in Cleveland, the Mariners have seen their grip on first place in the American League West slice from 10 games to 4 1/2, on the heels of the Astros heating up to a six-game win streak.

“At some point, if you keep stacking losses, you're going to have to change something,” said Ty France, who crushed his first homer since May 31 to tie the game in the fifth. “I don't think we're quite there yet. We look up, we still have a lead in the division. So we've just got to power through this and get back home.”

On paper, Tuesday looked like a promising matchup given that Seattle had its No. 1 starter, Castillo, going and Tampa Bay was without three key contributors -- Randy Arozarena (scheduled off-day), Brandon Lowe (day-to-day with a broken pinky toe) and Amed Rosario (left Sunday’s game after being hit in the face with a pitch).

Yet, the Rays wound up finishing with a season-high 11 runs, while the Mariners finished one shy of their season-high total of runs allowed (12 against the Brewers on April 7).

Tampa Bay ambushed Castillo for two runs early, including a Statcast-projected 397-foot homer from Yandy Díaz on Castillo’s first pitch of the game, which just barely sailed over the left-field foul pole to remain fair.

“La Piedra” was able to settle in after another run in the second -- until the fateful sixth, which he began with two straight one-out walks before he departed after his season-high-tying 103rd pitch.

That left the traffic to Baumann, who immediately served up a first-pitch triple to Taylor Walls that reached the right-field corner when Dominic Canzone laid out for but missed the hooking flyball. Then Baumann gave up a towering 392-foot homer on a fastball that was way above the zone but that Ben Rortvedt jumped all over.

That blew the inning -- and game -- wide open.

“The thing that I didn’t like about my performance was the walks that I had,” Castillo said through an interpreter. “I think those really hurt the team today.”

Indeed, for the second straight night, free passes were Seattle’s costliest culprit. Castillo was able to work around his first two, but the latter two prevented him from clearing the sixth despite his pitch count being intact, which put the onus on Baumann. Bolton, meanwhile, has almost exclusively been used in low-leverage situations, Tuesday being another example given the large deficit by that point. Same for Bazardo, who has an 8.78 ERA in 10 outings.

Such is the state of Seattle’s bullpen, especially on the heels of Bryan Woo’s early exit in the series opener -- which led to him being placed on the IL on Tuesday with a right hamstring strain -- and Bryce Miller being tagged for six runs and lasting just four innings on Sunday in Miami.

“We’re just not playing great baseball right now,” Mariners manager Scott Servais said.

Seattle’s offense has certainly had its warts on this trip, with an MLB-high 80 strikeouts since it began last Tuesday. But the pitching staff -- the bedrock to the club’s first-place standing -- has looked particularly vulnerable. Even accounting for Saturday’s 9-0 win on the shoulders of Logan Gilbert’s eight shutout innings, the Mariners have a 5.24 ERA, a 1.34 WHIP, a 2.82 strikeout-to-walk ratio and have been tagged for a .782 opponents' OPS.

They badly can’t wait to get home, where they are 27-12 and will begin a huge homestand against Minnesota, Baltimore and Toronto. But first comes one more in this road trip that they’d like to soon forget.