From MLB Trade Rumors:
The Mariners announce that they have designated pitcher Hector Noesi for assignment. The move clears space to add reliever Dominic Leone to the 25-man roster. The Mariners used six pitchers, including Noesi, to get through six innings of relief in a 12-inning game yesterday. (Noesi took the loss, giving up a walk-off home run to Coco Crisp.) Leone provides the Mariners with an extra arm in their bullpen.
Noesi, 27, has a 5.64 career ERA with 6.4 K/9 and 3.4 BB/9 in 191 1/3 innings, some of them as a starter. He pitched just 27 1/3 innings with the Mariners in 2013, spending much of the season in the minors. The Mariners acquired him from the Yankees in the Jesus Montero / Michael Pineda trade in early 2012.