The 26-year-old hit .120 (3-for-25) with a double and 13 strikeouts in 23 games this season before San Diego designated him for assignment on May 13.
Prior to being removed from a Major League roster, players selected in the Rule 5 Draft must clear waivers. If the player involved clears waivers, he must be offered back to the team that held his rights prior to being selected in the Rule 5 Draft. In this case, the Mariners and Padres agreed on a trade rather than having Blash returned to Seattle.
Blash appeared in 56 games with Triple-A Tacoma last season, finishing with 22 home runs and 47 RBIs. He is now expected to join Triple-A El Paso as he remains in the Padres' organization.
Ben Raby is a contributor to MLB.com and covered the Mariners on Wednesday.