The Blue Jays have not confirmed the injury. He took the loss against Tampa Bay Wednesday despite starting the game strong, striking out the first five batters he faced.
Estrada injured his back in February while working out, delaying the start of his spring training. The injury seemed to linger into the season, as the right-hander missed three weeks in July, including the all-star game, with a lower-back injury.
He’s struggled in the 10 games since then, compiling a 3-6 record and 5.47 ERA over 52.2 innings, with a .277 opponents’ batting average.
Those are in stark contrast to his pre-all star break numbers: 5-3 record, 2.93 ERA over 104.1 innings, .173 opponents’ batting average.