After a costly tantrum, the Boston Red Sox may be looking for bullpen reinforcements.

When Carson Smith threw his glove in anger and separated his shoulder last week, the Red Sox lost one of their setup options – the bridge to closer Craig Kimbrel.

That leaves Joe Kelly, who is on a roll, and Matt Barnes, who always seems on a tightrope.

Meanwhile, Blake Swihart is just sitting around as a useless No. 3 catcher. Why not trade him? The Red Sox soon will need to make room on their roster when Dustin Pedroia returns from the disabled list.

An impact trade is doubtful. Few teams are ready to give up on the season and trade a quality reliever. And a quality reliever won’t be cheap. Ask the Orioles about the price of Andrew Miller in 2014: They sent Eduardo Rodriguez to the Red Sox.

The Reds have closer Raisel Iglesias (asking price: the moon, plus two prospects) and veteran setup right-hander Jared Hughes (on a two-year contract with a 2020 option). The Padres have an enticing group of relievers. Closer Brad Hand and Craig Stammen are under contract beyond this year. Right-handed setup man Kirby Yates (0.64 ERA/0.86 WHIP) is up for arbitration next year and could be a target.

But are the Red Sox desperate for help? Heading into Friday’s game, Boston relievers ranked fourth in the American League in ERA (3.66) and third in WHIP (1.23).

Kelly had that meltdown in the season opener (four runs in one-third of an inning). Since then, in 20 innings: one earned run, 10 hits and five walks (0.75 WHIP) and 21 strikeouts.

Batters are hitting only .159 against Barnes (2.89 ERA/1.18 WHIP), but he’s yielded 12 walks in 182/3 innings.

Left-hander Bobby Poyner (2.08 ERA) has looked steady in his brief appearances, unlike right-hander Heath Hembree (5.31 ERA).

Hector Velazquez (1.80 ERA) has been a solid long reliever but is currently on the disabled list with a lower back issue. Former starters Brian Johnson and Stephen Wright are still searching for a role.

The Red Sox also have right-hander Tyler Thornburg, still rehabbing from shoulder surgery. He’s supposedly close to being activated, but anything he gives Boston will be a bonus. (Meanwhile, one of the players Boston traded to Milwaukee for Thornburg, Travis Shaw, has 10 homers this year.)

TRADING FOR relievers during the season can be a crapshoot. Think of Eric Gagne in 2007.

Bullpen help could come from Triple-A Pawtucket, and two lefties come to mind – Jalen Beeks and Robby Scott.

Beeks, a starter, is dominating with a 1.93 ERA and 59 strikeouts, and just 10 walks in 371/3 innings. Not sure how Beeks would adapt to relieving – but think back to 2013 when Brandon Workman began the season as a Sea Dogs starter and ended as a reliable reliever in the playoffs.

Scott has major league time and is dealing in Pawtucket (2.08 ERA, 21 strikeouts and two walks in 13 innings). Lefties are hitting .118 against him.

Austin Maddox, who surprised last year in a call-up to Boston (0.52 ERA in 13 games), is on the DL but is expected to begin rehabbing in Pawtucket.

Ty Buttrey, put on the 40-man roster during the offseason, has 30 strikeouts in 17 innings.

Workman is back in Pawtucket (1.03 WHIP in 211/3 innings).

REMEMBER WHEN Jeremy Barfield emerged last year with the Portland Sea Dogs while others, notably Cole Sturgeon, continued to grind away in the shadows?

Barfield hit 27 home runs in 92 games for Portland and was rewarded with a minor league free-agent contract and a starting assignment this spring in Triple-A.

Sturgeon hit .264 with a .705 OPS last year. Even though he was stellar in spring training, Sturgeon again was sent back to Portland.

Seven weeks into the 2018 season, the two outfielders have reversed directions.

Sturgeon was hitting .365 with six home runs in Portland and the Red Sox could no longer ignore him.

He was promoted to Triple-A on Monday.

An opening had to be created and Barfield – with his .132 average and two home runs – was vulnerable. The Red Sox planned to send Barfield back to Portland.

Barfield, who turns 30 in July, did not see that as a strategic career move. He asked for his release and eventually the Red Sox agreed. Now Barfield can look for new opportunities – maybe in Japan – while Sturgeon continues his underdog quest toward the major leagues.

Kevin Thomas can be reached at 791-6411 or:

kthomas@pressherald.com

Twitter: @ClearTheBases