‘The Gains That Could Be Made Would Be Enormous’

Major League Baseball’s lockout suspended the league’s drug testing program. Doping experts say the opportunity was there for players to take advantage.

Credit...Ronan LynamPHOENIX — When the 99-day work stoppage in Major League Baseball ended on March 10, the sport surged back to life. Delayed and truncated, spring training began within days. Free-agent signings and trades resumed almost instantly, and at a frenetic pace. Barred from team facilities during the lockout, players returned to clubhouses and fields.

Another familiar group was back at work: drug testers.

M.L.B.’s collective bargaining agreement — the five-year pact between the league and the players’ union that governs the sport —…