The other potential change looms at the utility position, where Taylor Motter appears to have edged into the lead at the moment over Shawn O'Malley in what loomed from the start as the closest competition in camp.
Here's the updated projections:
Catcher: Mike Zunino and Carlos Ruiz
This tandem seems to be working extremely well together, with the veteran Ruiz providing a nice mentor for Zunino as well as the pitching staff. Zunino appears far more relaxed this spring and has performed well both at and behind the plate.
First base: Daniel Vogelbach and Danny Valencia
The only change here is that Vogelbach has played well enough defensively to solidify his status and answered any doubt about whether he could platoon at first base. The question now might be how much Valencia plays at first if Vogelbach lives up to offensive expectations.
Second base: Robinson Cano
Again, he'll play this position as long as he's healthy.
Shortstop: Jean Segura
The offseason's biggest acquisition has been everything expected and provides a significant upgrade.
Third base: Kyle Seager
The only question is how often the Mariners can convince Seager to take a day off and let Valencia fill in to keep him fresh.
Seattle likes Motter's offensive potential as a right-handed hitter who runs well and has some pop, and that seems to have pushed him slightly ahead of O'Malley, a switch-hitter who filled in well last season. Both can play every position and it's possible both could be kept on the final roster if the club goes with one less outfielder. Mike Freeman initially was in the chase, but he was moved off the 40-man roster midway through camp and clearly is the third choice at the moment.
Outfield: Jarrod Dyson, Leonys Martin, Mitch Haniger, Nelson Cruz and Guillermo Heredia
If there were any doubts about Haniger's ability to handle right field on a regular basis, the former D-back has answered those with an outstanding camp. Martin has the center-field job and Dyson will play left field against all right-handed pitchers and some lefties. Heredia cooled a little after a strong start, but he's opened eyes as a right-handed complement to Dyson. But Cruz can also play right field at times and allow Haniger to shift to left if needed, so there is a potential scenario where they could go with the two utility players in Motter and O'Malley -- who both can play outfield as well -- and have Heredia open the season with Triple-A Tacoma.
Starting pitchers: Felix Hernandez, James Paxton, Hisashi Iwakuma, Drew Smyly and Yovani Gallardo
Those five have remained healthy to date and will be the rotation to break camp as long as that remains true, with Ariel Miranda the first option if needed.
Bullpen: Closer Edwin Diaz and right-handers Nick Vincent, Evan Scribner, Dan Altavilla and Casey Fien, plus lefties Marc Rzepczynski and Miranda
The one change here is the addition of Fien -- a veteran free-agent signee -- in place of Simmons, assuming his forearm issue pushes him onto the disabled list to open the season. Steve Cishek (hip) and Tony Zych (biceps) both have been working back from offseason surgeries and also will likely open the year on the DL, though Zych in particular doesn't appear too far away. Hard-throwing rookie southpaw James Pazos could fit into the mix if the Mariners decide to go with an extra reliever to open the season, which is possible if they opt for only one utility man and four outfielders.
The bullpen is also the one area general manager Jerry Dipoto might look to upgrade if he sees any options become available from other teams as they cut down their final rosters, as he did last year with the late addition of Vincent by trade from the Padres.