The backup catcher continues earning increased playing time as he's hit .330 with four home runs and 20 RBIs over his past 36 games since May 29, lifting his season average to a team-high .288.
"He's been as consistent as anybody we've had, especially against right-handers, obviously," manager Eric Wedge said. "He can drive the ball out of the ballpark, he gets big hits at the right time.
"And the one thing you know you're going to get from him is a quality at-bat. If you look at his at-bats, that's what we're looking to do with all our guys."
The Mariners are 5-1 while hitting .327 with 41 runs against the Royals in the past two weeks, with two more games on Saturday and Sunday. That success against Kansas City has propelled Seattle to an 8-4 record since July 16, improving its overall mark to 45-57.
Beavan was the beneficiary of the offensive help as he posted his second straight gem, giving up one run and four hits while striking out six over 6 2/3 innings. The big right-hander held Tampa Bay to one run and four hits in eight innings in his previous outing at Tropicana Field.
Beavan, 23, is 3-0 with a 3.05 ERA and one walk and 14 strikeouts in 20 2/3 innings since rejoining the club. That recent run has evened his overall mark at 6-6 with a 5.20 ERA in 15 starts.
"I'm pleased, but I'm not satisfied," Beavan said. "I want to keep building on each start and get back to where I need to be, which is competing and getting deep in the game and giving our guys a chance to win a ballgame every night."
The Royals have totaled just six hits and two runs in the first two games of the series and have now lost five of their last six in falling to 41-58, tied with the Twins for the worst record in the American League.
"To be honest, we're not swinging the bats real well right now," Royals manager Ned Yost said. "We're just not. But [Beavan] again threw strikes, didn't get himself in trouble walking guys and was ahead in the count for the most part."
The Mariners continued their recent trend of scoring early as Jaso's three-run blast in the first capped a five-hit inning against Royals right-hander Jeremy Guthrie, pitching his second game since being acquired in a trade from the Rockies.
The Royals got one back against Beavan in the second when Billy Butler singled, moved up twice on wild pitches and then scored on a sacrifice fly by Salvador Perez. Both wild pitches came on curve balls, which convinced Beavan to put that pitch away the rest of the night.
"My curveball was terrible today and I kind of banged that after the second inning and just worked slider-fastball," he said. "I just didn't have a good feel for it today. That's why you hope you have a couple other pitches. Fortunately, I had my slider working today."
Seattle responded immediately with two more runs in the bottom of the second on an RBI double by Dustin Ackley and sacrifice fly by Jaso.
Ackley again looked better at the plate, going 2-for-4 with a run and an RBI to give him four hits in two nights.
"I really don't think my swing has been that much different the last week, it's just a matter of squaring these balls up instead of popping them up," Ackley said. "It feels like everything the past week has been on the barrel. The past two days I've really beared down and barreled balls up and am getting the line drives I usually want."
First baseman Mike Carp also put together his second straight strong outing, finishing 2-for-4 with a solo home run in the sixth. Carp is 5-for-8 the past two games with three RBIs, improving his average to .186 as he continues coming back from a season-long shoulder issue.
"It looks like his timing is coming," Wedge said. "It's nice to see him drive one out of the ballpark tonight. Better swings, better balance. It takes some time to get your timing back and I think that's what we're seeing."
Jesus Montero went 2-for-3 and was hit by a pitch. The rookie designated hitter has feasted on Royals pitching, going 12-for-20 in five games this year.