MESA, Ariz. — A’s top shortstop prospect Jorge Mateo smacked his bat in frustration Friday during batting practice. He followed it up with a slight grimace, then a smile. He’d just gotten under a ball and hit a pop up, which happened to him a number of times on the day. With manager Bob Melvin looking on in the background, Mateo obviously was trying to impress his future skipper.



There’s nothing a player in Mateo’s position wants more than to make the major leagues — especially a young player of Mateo’s caliber who’s on the cusp of fulfilling a lifelong dream.



Prospects looking to make an impression aren’t going to blow away their coaches in one day, something A’s pitcher Daniel Mengden has come to grips with



“It’s always going to be hiccups in spring training,” Mengden said after his bullpen Friday. “We’re not going to be our best — we don’t want to be our...