Opposite dugout: Royals' arms present O's with another mound of challenges

Manager: Ned Yost, fifth year Record: 20-19 Last 10 games: 6-4 Who to watch: C Salvador Perez (.275/.333/.449, 4 HR, 12 RBIs); 1B Eric Hosmer (.304/.343/.418, 15 doubles, 18 RBIs); RHP Yordano Ventura (2-2, 2.34 ERA, 1.11 WHIP); RHP James Shields (5-3, 2.54 ERA, 1.08 WHIP) Season series vs. O's: 2-1, 16 runs scored, 6 runs allowed Pitching probables May 15: Yordano Ventura vs. Wei-Yin Chen, 8 p.m., MASN HD May 16: Jeremy Guthrie vs. Chris Tillman, 8 p.m., MASN2 HD May 17: Danny Duffy vs. Bud Norris, 7 p.m., MASN2 HD May 18: James Shields vs. Ubaldo Jimenez, 2 p.m., MASN2 HD Series breakdown The Orioles go from facing the American League's second-ranked pitching staff to taking on the AL's third-best set of arms when they head to Kansas City for a four-game series at the Royals. The O's offense continues to struggle to take flight and it won't be any easier against a Royals staff that ranks third in the AL with a 3.47 ERA and a 1.22 WHIP. Kansas City presents a strong rotation that has combined for a 3.45 ERA in helping the team near the season's quarter pole over .500. The Royals have pitched especially well lately in winning three in a row and six of eight. Over the last eight contests, Kansas City has allowed more than three runs just once and has held teams to one or less five times. The Royals have permitted just 16 total runs during that stretch. It helps that their starting five includes three of the AL's top 12 in ERA - rookie right-hander Yordano Ventura (2.34 ERA, seventh), right-hander James Shields (2.54 ERA, 10th) and left-hander Jason Vargas (3.00 ERA, 12th). The Orioles will see Ventura tonight and Shields on Sunday, but will miss Vargas in the series. In between, the Royals will start left-hander Danny Duffy (1-3, 1.96 ERA), who recently rejoined the rotation when former Oriole Bruce Chen went on the disabled list, and former Orioles right-hander Jeremy Guthrie (2-2, 4.80 ERA). The weekend at Kauffman Stadium is full of intriguing pitching matchups with Ventura facing Wei-Yin Chen tonight, Guthrie facing Chris Tillman on Friday and Shields going up against Ubaldo Jimenez on Sunday. The Royals' offense has been fairly shrug-worthy, sharing a similar quirk with the Orioles - both teams rank highly in average, but not in runs. Kansas City sits sixth in the AL with a .258 average, but is 13th with 156 runs. The Orioles are fourth in average and 14th in runs. But Baltimore won't likely have to worry much about the longball as the Royals have hit a major league-low 18 homers. There are still plenty of dangerous bats in the Kansas City lineup, even if they haven't all hit up to their own standards. Catcher Salvador Perez leads the club with a .783 OPS while tying Mike Moustakas with a team-best four homers. First baseman Eric Hosmer is batting .304 with 15 doubles and 18 RBIs. Shortstop Alcides Escobar is also a multi-tool threat with 13 extra-base hits, 11 steals and 17 RBIs. Outfielder Alex Gordon (.675 OPS) and Moustakas (.574 OPS) have underachieved. The Royals are winning with pitching, however. So for the second straight series, the Orioles' offense will be looking to get on track against a quality pitching staff performing at its best before going head-to-head with the first-place Birds.