BOSTON (CBS) — The Boston Red Sox have won five straight games. Two of those wins had a two-run margin of victory. The most recent two were won by a single run apiece.

Fortunately for the Red Sox, they have a “nasty boy” at the back end of their bullpen.

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While they may be an odd description of Matt Barnes, it is nevertheless what Dave O’Brien felt compelled to say on Tuesday night, after Barnes mowed down the Royals in order to secure his 18th save of the season and his third in five nights.

“Matt Barnes is a nasty boy!” O’Brien exclaimed after the final out. “He strikes out the side, and the Red Sox win it.”

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Barnes needed just 13 pitches to strike out all three Royals he faced. Eight of those 13 pitches were curveballs, and they generated four called strikes and two swings and misses. All three strikeouts came via the curveball, with the final two involving Salvador Perez and Ryan O’Hearn flailing helplessly at the breaking ball.

Barnes is now 18-for-21 in save opportunties this season, his first year as a closer. He’s been successful in four straight save opportunities, a solid recovery after blowing two saves earlier in the month (June 6 in New York, June 14 vs. Toronto). Barnes also took the loss on that wild-pitch loss in Tampa last week; he’s pitched three innings since, allowing two base hits while striking out four batters without walking anybody.

Barnes now ranks second in the American League with his 18 saves, trailing only Liam Hendriks, who has saved 21 games for Chicago. He entered Tuesday’s game after Adam Ottavino recorded his AL-leading 15th hold with a scoreless eighth inning. Darwinzon Hernandez recorded his 10th hold of the season with a scoreless seventh, too. Yacksell Rios, whom the Red Sox acquired in the middle of the month, recorded his second victory with Boston, after he relieved starter Nick Pivetta and kept the Royals off the board for 1.2 innings.

“Bullpen’s been throwing the ball really well. I think for the vast majority of the season, the bullpen has been really solid,” Barnes said. “We’ve got some guys on there with a bunch of experience, we’ve got some young guys who have absolutely electric stuff. But it doesn’t really come as a surprise, honestly. I kind of saw it in spring training. Obviously things don’t always pan out the way that you kind of expect them to or want them to. But I think this has been awesome. Guys are feeding off of each other, guys are doing their thing, wanting the ball, competing, and going out there and doing their job in big situations. It’s been awesome. It really has.”

The tremendous first half of the season has Barnes as a legitimate candidate for the AL All-Star team. That’s an honor that Barnes would welcome, but he said he’s not wholly focused on that matter.

“I mean it would be awesome. It really would,” Barnes said. “I don’t know that I’ve given a ton of thought to it. I mean honestly it’s probably crossed my mind here and there. But at the end of the day I still gotta go out there, I gotta get the job done in the ninth, I have to go out there and compete. And we’re trying to win ballgames. If it happens, it happens. It’s kind of out of my control, right? I don’t know what the exact process is for pitchers. But if I go out there and continue to take care of business and do my job in the ninth, if it happens, awesome. If it doesn’t, I’m gonna go home for a few days and sit on the couch. So like I said, it would be awesome, and I’d be very fortunate to do that. But if not, then you know, it is what it is.”

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Whether or not he’s an All-Star, the Red Sox broadcast team and the Royals have to agree: Matt Barnes is nasty.