Brandon Belt - 1 year $13-$15 million
Where Solano is my personal favorite, Brandon Belt is by far the most impactful player on this list. In 2023, Belt was worth 2.3 wins according to fangraphs. He had a real bounce back year after a disappointing 2022, slashing, .254/.369/.490 with 19 home runs. He draws walks at an elite rate, 15.1% BB%, even though his strikeout is pretty high, 35% K%. He would add a very valuable bat to the middle of the lineup, most likely spending a majority of the time at DH, while give you insurance if Ty France doesn't perform again.
Adding a bat like Brandon Belt would be a really solid bat to add to the middle of the order. Again, hopefully he is the 2nd or 3rd biggest bat they acquire this offseason, but he would help lengthen this lineup tremendously. Mike Ford, AJ Pollock, and a trio of La Stella, Trammell, and Hummel combined for nearly 500 plate appearances. You can see a theme here that the Mariners gave way too many at-bats to guys that should not have had those at-bats. Replacing those 500 plate appearances with a bat like Belt would improve this team so much!
The Mariners were rumored to be one of the finalists for Brandon Belt last offseason before he signed with the Blue Jays. I expect Dipoto to be involved in the Brandon Belt sweepstakes this year as well. Belt is a west coast guy and maybe coming back and playing in the PNW will be a wish for Belt after his first season back east. Belt signed a 1 year $9.3 million dollar deal with the Blue Jays coming off a poor 2022 season. Belt will most certainly take a 1 year deal and command a raise. I think the Mariners could pull him away from the Blue Jays with something in the $13-$15-million-dollar range.