Major League Baseball is investigating four recent positive tests for the steroid stanozolol along "the same model" as its 2013 Biogenesis probe, according to Rob Manfred.

Jenrry Mejia was suspended for 80 games Saturday, the fourth player in 16 days banned under the Major League drug program following a positive test for stanozolol.

Mejia's discipline came after positive tests and suspensions for Ervin Santana, David Rollins and Arodys Vizcaino.

"Other than the similarity of substance, I have no reason to believe right now that they're connected," Manfred said. "Having said this, whenever we have a series of tests for a single substance, we undertake an investigative effort to determine whether there's a connection and what that connection might be. If you look back, the very beginning of Biogenesis was the fact that we had a series of testosterone positives that began our investigative process, so we'll follow that same model."