The Mariners are struggling. Times are bad, especially in the rotation, where it feels like everyone is either currently injured or likely to be in the near future. Other than those injured folks coming back, there's no real hope on the horizon.
This team was built to win this year, but it wasn't built to withstand injury, as we've seen. When Leonys Martin went down, who was there to replace him? Triple-A Hero Stefen Romero. When Ketel Marte went down, the team turned to Luis Sardinas and Chris Taylor, neither of whom are able to truly play at the big league level. It's not just the injuries, either. There is a lack of depth overall; if someone struggles, there's no real options worth trotting out to replace them. Norichika Aoki has been disappointing, for example, but unless you're willing to give BOOG! Powell an opportunity, there's no one in the minors that can take his place.
The only place this team built in some semblance of depth is the rotation. James Paxton spent the first couple months in Triple-A, not because he wasn't worthy of a rotation spot, but because the team had players who were better suited for the role. When Felix went down, there was an option. When Wade Miley hit the DL, though, the cupboard was bare. Don't forget, if Hisashi Iwakuma hadn't come crawling back after failing his physical, the depth that Paxton provided likely would have never existed.
This isn't to say that the team made the wrong moves this offseason. They leveraged minimal available assets to put a competitive product on the field while Felix, Robinson Cano, and Nelson Cruz could still contribute at a high level. But these are the seeds that were sowed. In order to contend this year, the team had to forget any chance of depth to have a chance at a quality starting lineup. But when the team is felled by injuries, no one should be surprised.