ST. PETERSBURG, Fla. -- If Blake Snell can take his promising starts during the second half of the season into 2018, the Tampa Bay Rays could be legitimate playoff contenders.

Snell had a career-high 13 strikeouts and Curt Casali hit his first home run of the season to lift the Tampa Bay Rays to a 6-0 victory against the Baltimore Orioles on Sunday at Tropicana Field.

The Rays swept the Orioles and closed the season winning four straight to finish 80-82, a 12-game improvement from last season.

"You want to see guys with smiles on their faces and we saw a lot of smiles today after the game," Rays manager Kevin Cash said. "It's about winning. So I'm thrilled that we finished strong and won this final one. But I can't lie and say there's not some frustration and disappointment (about missing the playoffs).

Baltimore (75-87) lost five straight games to close out its 2017 campaign with a last-place finish in the American League East.

After spending the first half of the season between the Rays and their Triple-A affiliate in Durham (N.C.), Snell (5-7) went 5-1 in his last nine starts and arguably saved his best stuff of the season for Sunday's finale.

Snell retired the first 12 hitters and struck out two batters in six of seven innings. He allowed two hits and threw 100 pitches in the seven-inning outing with 71 strikes.

"It was a good day, I needed to get this start and finish strong," Snell said. "It's a good way to end but I have a lot of work to do this offseason and heading into the spring. A lot to like (from this start) and a lot to learn from it."

The Orioles only got hits from Manny Machado, Trey Mancini and Mark Trumbo, and never had a runner reach second base.

"Obviously Snell is a good pitcher and you can see why he is so highly thought of," Orioles manager Buck Showalter said. "But we haven't been swinging the bats well. We scored three runs in the last 27 innings. It's been a challenge for us lately."

Casali led off the bottom of the fifth inning with a home run to left field on a 3-1 pitch from Orioles starter Kevin Gausman to give the Rays a 1-0 lead.

Gausman (11-12) gave up six hits and struck out nine over seven innings.

"No walks today, obviously I was trying to be efficient and make them put the ball in play," Gausman said. "I wanted to get my innings up and got close to 190 innings. Obviously this season didn't go like I wanted it to but it was nice to end it on a good note."

Tampa Bay increased its lead against Orioles reliever Brad Brach. Third baseman Evan Longoria roped a double to right field that scored pinch runner Peter Bourjos and Logan Morrison added an RBI single to make it 3-0.

Brach's struggles continued as he walked Steven Souza Jr. to load the bases with one out and walked Trevor Plouffe to bring Longoria home and give the Rays a 4-0 lead. Brach was replaced by Mike Wright, who proceeded to walk Casali to make the score 5-0.

Mallex Smith's sacrifice fly to center scored Souza Jr. to complete the five-run outburst.

"We have a lot to build off of," Longoria said. "Seeing Blake Snell finish the way he did was awesome. We're going to have pitching again (next year). I don't think anybody should be happy if you don't make the postseason. I felt like we had a pretty good group. We were just unsuccessful. We weren't able to put together the runs when we needed to."

NOTES: Tampa Bay Rays pitchers struck out 18 Baltimore Orioles batters. ... Rays OF Kevin Kiermaier (sickness) was held out of Sunday's game. ... Orioles OF Adam Jones did not play Sunday, opting to rest his sore legs. ... Rays C Curt Casali's last home run came on September 27, 2016, against the Chicago White Sox off Chris Sale. ... The announced attendance Sunday was 16,018. The Rays drew 1,253,619 this season.