The rookie Melendez blasted it an estimated 406-feet to right field which bounced into the fountains to give the Royals a 5-0 lead.
Melendez is putting together quite the campaign after being called up on May 3. He's hit 13 home runs on the year and has back-to-back homer games four times this season. Among rookies, he's hit the fifth most home runs this season and is just two behind teammate Bobby Witt Jr.
''Just being relaxed helps the confidence and just telling myself that definitely helps,'' Melendez said. ''It prevents me from over thinking. I knew that we can do this and it was just a matter of time with getting comfortable.''
The 7-8-9 hitters of Michael Massey, Nate Eaton and Kyle Isbel provided most of the production as they went a combined 6-for-9 with nine runs scored and five RBIs. All 13 RBIs came from rookies.
''When you start winning games, the energy starts getting bigger and bigger,'' Eaton said. ''You just take that into the next series and that'll hopefully make it really great.''
Brad Keller (6-12) had his 11th quality start of the season, going six innings, allowing one run on four hits while walking three and fanning four.
''It was hot, but our defense was unbelievable today and it was a lot of fun,'' Keller said. ''The offense exploded which was a lot of fun to watch so it was good.''
Rafael Devers put the lone blemish on Keller's line when he hit his 24th homer of the year, sending one 441-feet into the right field fountains. Tommy Pham hit a towering 427-foot two-run homer to left field off Taylor Clarke in the seventh.
''Offensively, we hit the ball hard today which is good,'' Red Sox manager Alex Cora said. ''I just think pitching wise we have to be better...Overall, it's not excuses, we just have to play better.''
Kutter Crawford (3-4) allowed five earned runs over five innings on five hits, struck out four and walked two. Darwinzon Hernandez gave up five runs, five hits and four walks in the eighth inning.
''Just the command, not having the greatest feel and you fall behind and I just had a hard time getting back into counts,'' Crawford said. ''They were coming out swinging early.''
With the youth movement in full bloom in Kansas City, they have won four of their last five home series and it's the first time the Royals have won a four-game set against Boston since 2013.
''I think the chemistry is a big part of it,'' Melendez explained. ''A lot of these guys have played together for a while and that's going to help our chemistry of course. We have a lot of confidence in the guys behind us.''
''We're watching a group of younger players not afraid to take a walk in big situations and pass it off to the next guy,'' Royals manager Mike Matheny said. ''I think we only had one missed opportunity today...guys are taking a lot of pride in getting runs in.''
Red Sox: hosts Atlanta for a two-game series starting Tuesday.
Royals: continues their season-high 11 game homestand as they host the Chicago White Sox on Tuesday in a doubleheader.
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