And the roll continues. In fact, the Royals are looking better and better after winning Friday for the ninth time in 10 games with a 7-2 victory over the Tampa Bay Rays at Tropicana Field. Sure, the Royals displayed the best parts of their recent formula — a strong outing by a starting pitcher (Luis Mendoza) and airtight bullpen work. But now, for the second game in a row, they featured some long-awaited pop. “The (pitchers) have been feeding off each other,” designated hitter Billy Butler said, “and we’re starting to get in the mix offensively. It’s been a fun stretch here.” Butler paced an efficient 10-hit attack with two singles and three RBIs. Salvy Perez added two hits and two RBIs. The Royals were five for 11 with runners in scoring position after going six for 12 in Thursday’s 10-1 victory. “Since we moved Salvy into the three (hole in the lineup),” manager Ned Yost said, “he and Billy have been a real nice tandem. And Hos (Eric Hosmer) has picked it up.” All of that, plus Elliot Johnson continued to bedevil his former teammates by getting two more hits, including a game-tying triple in a four-run fifth inning. “Realistically, this offense we have here,” Johnson said, “we should be scoring five, six, seven (runs) every night. We really should. These guys are really talented.” Butler’s three RBIs boosted his career total to 517 and moved him past Carlos Beltran into eighth place on the franchise’s all-time list. “That’s pretty good company,” Butler said. “Beltran is a great player, and he’s still doing it today. I remember watching him play in a Royals uniform. He did a lot of great things. Got a lot of big hits.” The Royals erased a 2-1 deficit with a four-run fifth inning against Rays left-hander Matt Moore. And when Mendoza found trouble in the seventh, they turned to their impregnable relief corps for three scoreless innings. The result was a 13th straight game of holding an opponent to three runs or fewer, which extended a club record and ranks as the best streak among American League teams since Toronto on 1991. Mendoza, 2-3, weathered that shaky two-run first inning by carrying a 5-2 lead into the seventh, which Desmond Jennings started with a double past third. An infield single by pinch-hitter Luke Scott brought Aaron Crow into the game with no outs and runners at first and third.