Anderson is scheduled to start Saturday's game against the Rangers.
Anderson had been in line to pitch his final game for the Pirates on Wednesday, but he was scratched from his scheduled start after Pittsburgh agreed in principle to send him to Philadelphia. The deal was scrapped after one of the Pirates was dissatisfied with the medical reports of one of the Phillies prospects they were set to receive in return, but Pittsburgh quickly found another willing trade partner in Seattle, who sent minor leaguers Carter Bins and Joaquin Tejeda out to acquire Anderson. The 31-year-old southpaw hasn't been a major fantasy asset this season with a 4.35 ERA, 1.20 WHIP and 86:25 K:BB across 103.1 innings, but he should at least add some stability to the back end of a Seattle rotation that has been hit hard by injuries.