As promising as the Red Sox have looked at times, and as much progress as their young players have made, the club ultimately hasn’t been able to escape the gravitational pull of .500.

Fittingly, the Red Sox concluded what has been a thoroughly middling season in fittingly middling fashion, beating the Tampa Bay Rays 3-1 to finish exactly 81-81 on the year.

In doing so the Red Sox clinched third place in the AL East and avoided a third straight losing season, but while the club took a step forward after back-to-back last-place finishes, the Red Sox still fell short of their biggest goal — making the playoffs and competing for a championship.

Still, the club has provided reasons for optimism, several of which were on display Sunday.

With the season winding down the Red Sox handed the ball to Quinn Priester, the 23-year-old right-hander acquired at the trade deadline in exchange for former first-rounder Nick Yorke. Though technically no longer a prospect — he’d already appeared in 20 MLB games with the Pittsburgh Pirates before July’s trade — Priester is one of the most promising young arms in the Red Sox system, and Sunday offered the up-and-comer a little taste of pitching at Fenway Park.

By and large, Priester delivered.

The young righty looked like he belonged in his first start with the Red Sox, allowing one run over five innings on four hits and a walk. He threw 58 of his 89 pitches for strikes, and though he only struck out two batters, he generated nine whiffs and consistently kept Tampa Bay hitters off balance with his slider and sinker.

The Red Sox gave Priester an early lead after scoring twice in the bottom of the third inning. Jarren Duran singled and came around to score on an error following Vaughn Grissom’s subsequent double. Triston Casas then scored Grissom on a fielder’s choice, making it 2-0.

Boston fell victim to some poor defense in the fourth when Josh Lowe scored on a throwing error by Red Sox shortstop Nick Sogard, but Tampa Bay returned the favor in the fifth by botching what should have been a routine double play by Connor Wong. Second baseman Richie Palacios fumbled the lob from shortstop Jose Caballero and came off the bag, allowing Grissom to score from third.

That wound up being all the offense the Red Sox needed.

Josh Winckowski, Luis Guerrero, Chris Martin and Justin Slaten combined for four scoreless innings to close out the Red Sox season, a strong finish for a bullpen that endured some rough growing pains in the second half. Guerrero in particular capped off what has been a stellar September audition, throwing 10 scoreless innings over his first nine MLB appearances.

And Slaten, possibly Boston’s closer of the future, wrapped up his highly successful rookie season by locking down his second career save.

Now comes the offseason, and the club hopes brighter days ahead.

Cora shouts out Mellor

Dave Mellor, Fenway Park’s longtime head groundskeeper, is retiring after 23 years with the Red Sox and 39 years in baseball. Prior to Sunday’s finale, Cora offered a heartfelt tribute to Mellor, who he described as a consummate professional and one of the hardest working people he’s ever met.

“We work hard. We do. We all do. Nobody works harder than that guy. Think about all the concerts. We go on the road and there’s five concerts here and that field is ready to go six days later. It’s amazing,” Cora said. “Last year the rain delays and the doubleheaders, and that guy is just grinding out there. He’s amazing. The schedule, the visiting team early work and the Savannah Bananas, all the stuff that we do here, it’s amazing.

“The guy is a workaholic, he’s always on top of the game, just communicating with us, with Ramon, kind of like what we’re going to do,” he continued. “I hate when I see him with the iPad on the field. Hated it as a player and hate it more as a manager. But shoot, what a career.”