No. 3: Luis Rengifo
Ironically, the Mariners actually signed Rengifo as a free agent in March of 2014 but was sent to the Rays and then to the Angels in a pair of trades. Rengifo is one of my personal favorites on this list and could really transform how this lineup goes about producing runs.
Rengifo has an impressive 126 wRC+, following up a really solid 114 wRC+ in 2023. He is slashing .315/.358/.442 with six home runs and 22 stolen bases. Rengifo would add a very high average, speedy second baseman who gets on base at a solid rate. He would slot in so well at the top of the Mariners lineup and would provide so much athleticism and speed that this lineup just doesn't have, setting up the middle of the order to drive in some runs.
Perhaps the biggest roadblock in a Rengifo deal is the fact that he is the American League West. The 27-year-old second baseman is only under control through next year, so the Angels could look to capitalize on a career year and limited market, but it could cost the Mariners a decent prospect haul. The Angels are a weird team and under the leadership of Jerry Dipoto, the Mariners and Angels have never completed a trade. It would be awesome to see that change and Rengifo wearing a Mariners jersey come August, but the odds don't seem great.