Casey Tefertiller

The 2019 fourth-round catcher impressed the A’s during his time in spring training and summer camp.

The 2017 second-rounder owns huge raw power that he intends to access more in games thanks to a swing that is now more in sync.

The A’s will let the big lefty loose on the American League this season with improved control and a wider arsenal.

The A’s worked out a deal to acquire Machin, their top target in the Rule 5 draft, because they value his hitting ability and versatility.

Innovative, creative and caring, Lieppman spent 28 years as the Athletics’ farm director.

The 17-year-old Colombian hit his way to the Arizona League, where he showed a wide range of skills on both offense and defense.

With longtime farm director Keith Lieppman retiring, Ed Sprague Jr. takes the reigns of Oakland’s innovative player development department.

Oakland righthander Brady Feigl is testing his stuff against advanced hitters in the Arizona Fall League.

A rough first half at Triple-A in 2018 helped point the way forward for Neuse at the plate.

A 25-year-old righthander, Romero could provide the A’s with some late-season bullpen help down the stretch.

Promoted to Triple-A Las Vegas for the first time on June 9, Heim is enjoying a breakout season in 2019.

The 23-year-old is hitting a career-best .314/.352/.573 with seven home runs and 11 stolen bases with Triple-A Las Vegas.

The 88th overall pick in the 2016 draft, Murphy is off to a strong start for Triple-A Las Vegas this season.

The 20-year-old shortstop has been focusing on adding muscle and improving his approach at the plate.

A behind-the-scenes look at the Oakland Athletics franchise through the years as told by radio voice Ken Korach and beat writer Susan Slusser.

What the overlooked righthander lacks in “wow” stuff he makes up for with smarts, toughness and results.

Rivas can hit for average and stands out defensively at first base, but he faces questions about his power production.

The Athletics were pleased with Eierman’s pro debut after drafting the Missouri State shortstop with the 70th overall pick in 2018.

Bolt used a rough introduction to Double-A as a springboard to retool his swing. It paid off in a 40-man roster spot.

From platooning to bullpening, Bob Melvin is a leader for all the situations presented in Oakland.