The firing of a top union official is stirring concerns among powerful industry forces at a sensitive time in the game’s labor history.



The Major League Baseball Players Association’s dismissal of attorney Rick Shapiro on July 19 has brought a cascade of complaints from a faction of unhappy agents. Among those complaints: a suspicion that agent Scott Boras’ influence is reflected in the firing, and that his power is growing inside the union.



Oddly, and perhaps unwittingly, those agents are aligned with another party: Major League Baseball. Some league officials viewed Shapiro as both knowledgable and a dealmaker.



The term dealmaker is open to interpretation. To some, it hints that Shapiro was more likely than other union leaders to acquiesce to MLB’s desires.



To others, it means that Shapiro, a contract and arbitration expert who helped negotiate the 2012 and 2016 collective bargaining agreements, could have played a key role...