Before the Oakland A’s played on Sunday, manager Mark Kotsay addressed the team in the clubhouse and, in a very cool way, informed them that Brent Rooker had made the All-Star Game, voted in as a DH by his peers. Rooker, the former Mississippi State slugger, buried his face in his hands as his teammates applauded and cheered. (Watch the video; it’s emotional.) Rooker went to spring training with the A’s — his fourth organization in a year’s time — unsure of a roster spot. He not only made the club but was one of baseball’s hottest hitters in April, batting .358 with nine homers and 22 RBIs that month. He has cooled off of late (.191, three homers, 39 strikeouts in his last 30 games), but Kotsay stressed that Rooker was deserving of the All-Star nod and hailed his “perseverance and grit” in getting to where he is. “It’s overwhelming,” said Rooker, seemingly as humble a guy as you could hope to meet. He thanked his teammates for making him feel welcome as a newcomer in the spring. Rooker didn’t start Sunday’s game but entered as a pinch hitter and belted his team-leading 14th homer in the A’s 8-7 loss to the Chicago White Sox. He is batting .243 with 41 RBIs, also a team-high. P.S. Fingers are crossed in Baltimore after Jordan Westburg, the rookie out of MSU, was hit by a pitch on the left arm Sunday. He was expected to undergo an MRI. The HBP came with the bases loaded in the eighth inning and pushed the winning run across in a 2-1 victory against Minnesota. It was Westburg’s third RBI in six games in the majors; he is batting .263. He stayed in the game at second base in the ninth. … Braden Montgomery, the Madison Central High product and current Stanford star, hit a two-run homer for Team USA in a 10-0 romp over Chinese Taipei. He is 2-for-12 in the team’s three games to date; he has not yet pitched in the series.