The Mariners have placed righty David Phelps on the 10-day DL, per a club announcement. He’s dealing with what the team is calling an elbow impingement and is expected to be sidelined for two or three weeks. Meanwhile, the club further announced that starter Felix Hernandez has been diagnosed with shoulder bursitis that will keep him out for three to four weeks.

With the DL placement of Phelps, Seattle has cleared way for the activation of just-acquired first baseman Yonder Alonso. He’ll suit up against his former team, the Athletics, in tonight’s action.

Of course, the M’s had only just acquired Phelps, too. It certainly hurts to see the organization’s top deadline acquisition head out of action so soon after he had joined the team. That said, it seems promising that he was not deemed to have a more serious elbow issue. Since coming to Seattle, Phelps has made seven appearances, allowing two earned runs over six innings while racking up 11 strikeouts and just one walk.

Hernandez had already gone on the DL a few days ago, with the team stating at the time that he was dealing with biceps tendinitis. With the new diagnosis — a repeat of an injury that drove King Felix to the DL for about two months earlier this year — it seems a lengthier absence is to be expected. That comes at an inopportune moment, as Hernandez had picked up his output over July, working to a 3.86 ERA with 36 strikeouts and 14 walks in 35 innings.

As Seattle welcomes Alonso to the fold, it sits just one game out of Wild Card position. But the club’s pitching health and depth have continued to be a problem. Hernandez returns to a disabled list that already includes Hisashi Iwakuma and Drew Smyly. Just-added southpaw Marco Gonzales took a spot start for Hernandez, but he was knocked around. Other 40-man members who have taken starts in the majors this yearinclude Andrew Moore, Sam Gaviglio, and Chase De Jong.