The Seattle Mariners are having a good season, sitting at 51-45 and trailing the Houston Astros by one game in the American League West at the All-Star break. Although they are doing well, the M's could still make some adjustments at the 2025 MLB trade deadline. As the end of July draws near, the Mariners' trade deadline needs include targeting one big player.
Seattle still has a solid rotation, despite struggling with injuries. Bryan Woo is 8-4 with a 2.75 ERA over 18 starts. Likewise, Logan Gilbert has remained solid, with a 2-3 mark over 12 starts and a 3.39 ERA. Luis Castillo continues to produce, going 6-5 with a 3.41 ERA in 19 starts. While George Kirby has not had a great season, he is still an above-average pitcher. He is 4-4 with a 4.50 ERA in 10 starts. Meanwhile, Logan Evans has gone 3-3 with a 3.75 ERA over nine starts, emerging as a reliable starter.
The bullpen has remained steady, ranking 11th in team ERA. Andres Munoz has led the charge, going 3-1 with a 1.50 ERA and 21 saves. While he has also blown six games, he is still the closer. Carlos Vargas has been steady in the back of the bullpen with 11 holds. Additionally, Gabe Speier and Matt Brash each have 10 holds while steadily pacing the back of the pen.
Cal Raleigh has smashed records and is the best hitter in the Seattle lineup. So far, he is batting .259 with 38 home runs, 82 RBIs, and 65 runs. If Raleigh continues at his pace, he would finish with 65 home runs, 141 RBIs, and 155 runs, which would all be records for a catcher. Amazingly, he has morphed into one of the most dangerous sluggers, almost overnight.
J.P. Crawford is also having a revival season, batting .290 with seven home runs, 37 RBIs, and 44 runs. Likewise, Randy Arozarena has done well, hitting .251 with 17 home runs, 48 RBIs, and 53 runs. Julio Rodriguez continues to hit home runs off great pitchers, batting .252 with 14 home runs, 50 RBIs, and 63 runs.
The M's are clearly better on offense than they have been in a while. Yet, despite that, there are still issues that could arise. Their offense is currently hot, but inconsistent. Notably, first base is the biggest Mariners' trade deadline need right now, with Luke Raley and Donovan Solano making for a mediocre duo.
Therefore, it might be prudent for the M's to target a first baseman who could help. Third base could also be an issue. However, the M's might go after first base to solidify the position to make a playoff run. While the M's could target Eugenio Suarez, there is another Diamondback slugger who is a better fit.
The Mariners could trade for Josh Naylor at the MLB trade deadline

Josh Naylor has had a fantastic season, batting .294 with 11 home runs, 58 RBIs, and 46 runs while leading the Arizona Diamondbacks. Unfortunately, the D-Backs are also 47-50 and unlikely to make the playoffs unless they go on a massive run. Because of this, Naylor is a potential trade target.
The Mariners have been linked to Naylor, and he would be the perfect fit in Seattle. Additionally, it would be someone who could protect Raleigh in the lineup. Whereas Arozarena currently is the cleanup hitter, Naylor would likely occupy that spot if the Mariners were to acquire him. If the Mariners trade for a player like Naylor, it would help their playoff chances.
While the M's are doing well, they are not exactly locked into a playoff spot. Currently, they are clinging to the final AL Wild Card spot, leading the Tampa Bay Rays by 1 1/2 games. For the Mariners to continue to climb the standings, they need consistent hitting from their lineup. Naylor would provide that.
Although Naylor is not perfect, his stats have been stellar. Baseball Savant ranks Naylor in the elite tier in terms of strikeout percentage. Moreover, his squared-up percentage is in the 87th percentile. His expected batting average is also in the 92nd percentile, showing how good he has been at the plate. Likewise, his batting run value is above average, and he continues to produce despite the struggles in the rest of the lineup.
If the Mariners trade for Naylor, it won't be a cheap move. Ultimately, Seattle would likely have to give up at least two top prospects and likely even more. If the M's want to mix in an MLB-ready player, they could likely have that available in the deal.
With the MLB trade deadline fast approaching, the Mariners must act quickly if they want to achieve the results they desire. Naylor could be the final piece of the puzzle, and his playoff experience would also serve as a big advantage for Seattle. Naylor could also solve the biggest flaw in the Mariners' lineup.