4 reasons the Mariners are thriving, and 4 things holding them back

The 2025 Seattle Mariners have been a roller coaster of a team to follow. One night they look like a juggernaut — crushing home runs, stealing bases, shutting down lineups. The next, they look like they couldn’t buy a hit with runners on base if they tried.

Mariners fans are already riding the ups and downs, and we’re only in April. But why is this team so hot and cold? Let’s break it down with four key reasons they’re thriving and four big reasons they’re still being held back.

4 reasons the Mariners are thriving

Power output

Let’s start with the long ball. Through the early part of the season, the Mariners have launched 34 home runs — tied for the fifth-most in Major League Baseball. That’s no small feat, especially for a team playing half its games in the pitcher-friendly confines of T-Mobile Park.

This power surge hasn’t come from just one or two players either. Though largely carried by Cal Raleigh (MLB-high-tying nine home runs) and his torpedo bat, Dylan Moore (five) has been on a tear recently and guys like Randy Arozarena, Jorge Polanco and Rowdy Tellez (four each) have added to the cause. Julio Rodríguez's career norm of struggling through April continues (three homers), though an 11.8 walk percentage might indicate a more mature plate approach.

Outside of Raleigh, everyone else's power output makes it harder for opposing pitchers to pitch around anyone in particular. When a lineup can hit from top to bottom, it only takes one mistake to flip a game. The home run ball has given the Mariners a way to score in a hurry — something that’s especially valuable when the offense is otherwise struggling to string together hits.

Old School baseball

One thing that has nearly left the game of baseball is the stolen base. Another way to put yourself in scoring position, this is something that Seattle hasn't taken advantage of in the past.

As things currently stand, the Mariners are using the stolen base to full effect, thanks in large part to a new face. With 33 stolen bases so far (third-most in the majors), Seattle has embraced a more aggressive style of play. Gone are the days of station-to-station baseball, waiting for the long ball; now, they’re swiping bags, taking extra bases, and putting constant pressure on opposing batteries.

This isn’t just about raw speed either. It’s about timing, instincts, and knowing when to take a risk. Even guys you wouldn’t peg as burners are getting in on the action, as Raleigh is notably on pace to break the Mariners catcher stolen base record (seven) with three already. This aggressive approach forces pitchers to divide their attention, keeps defenses on edge, and creates more opportunities to score without needing a hit. It’s also a perfect complement to their power: if the home runs aren’t flying, they can still manufacture runs the old-fashioned way.

Continued patience at the plate

One of the most encouraging signs from this Mariners squad is their discipline at the plate. With 103 walks (fourth in the league), the team has shown a real willingness to grind out at-bats and wait for their pitch.

This is a stark contrast from recent years, when impatient approaches and chasing pitches out of the zone were constant issues. Now, Mariners hitters are taking what pitchers give them and forcing them into deep counts. The benefits of this approach are twofold: not only does it lead to more baserunners and scoring opportunities, but it also wears down starting pitchers faster and brings bullpens into the game earlier.

Patience at the plate is contagious, and it speaks to a lineup that’s buying into a smarter, more sustainable offensive philosophy. Even when the hits aren’t falling, drawing walks gives this team a fighting chance in every inning.

Keeping it on the ground

On the pitching side, the Mariners are doing something extremely well: keeping the ball on the ground. Their pitching staff leads the American League with a 47.4 ground-ball percentage, which is a huge reason they’ve been able to stay in games. Ground balls typically result in weaker contact, fewer extra-base hits, and plenty of double play opportunities — exactly what you want if your defense can handle it (we’ll get to that part later).

The starters, in particular, have been effective at pounding the strike zone low and inducing grounders. Logan Gilbert has made a habit of generating soft contact, while the bullpen has followed suit with sinkers and sliders designed to keep the ball down. This ground ball approach limits big innings and keeps pitch counts low, giving the Mariners a chance to stay competitive even on nights when their offense isn’t firing on all cylinders.

4 things holding them back

Worst team with RISP

If there’s one stat that tells the story of Seattle’s early-season frustrations, it’s this: a .191 batting average with runners in scoring position. That’s not just bad — it’s second-worst in Major League Baseball ahead of only the Chicago White Sox.

It’s not because they’re not getting chances. Thanks to all those walks and stolen bases, they’re putting guys on base. But when it comes time to deliver the big hit, they just can’t seem to do it. Whether it’s pressing at the plate, bad luck, or simply poor execution, the inability to cash in is killing them. Games that should be comfortable wins are turning into nerve-wracking nail-biters — or outright losses.

It’s a morale killer, too. There’s nothing more deflating than loading the bases with one out and coming away empty. This team doesn’t need to lead the league in batting with RISP, but if they could just be average, they’d probably have several more wins already.

Pitching staff has been mediocre

For a team that has prided itself on elite pitching the past few seasons, a 3.96 ERA is underwhelming. It puts the Mariners right in the middle of the league at 15th overall. That’s not a disaster, but it’s not what fans expected from a rotation that includes Logan Gilbert, Luis Castillo, Bryce Miller and Bryan Woo.

Part of the issue has been inconsistency. Some nights, they look like aces, other nights they’re getting hit hard early. The bullpen hasn’t exactly been lights out either, with some games slipping away late.

When the pitching falters and the offense isn’t converting with runners on, it creates a perfect storm of disappointment. The Mariners don’t have the kind of lineup that can routinely win shootouts, so their pitchers need to be better than average. Right now, they’re not quite there.

Uncharacteristically bad defense

Defense used to be a hallmark of Mariners baseball, but so far this season, it’s been a major problem. The gloves have gone cold, resulting in errors, missed double plays, and poor positioning. Whether it’s routine grounders turning into infield hits or outfielders misplaying balls in the gap, the defensive breakdowns are costing this team runs and momentum.

When your pitching staff leads the league in ground ball rate, strong infield defense is critical. But Seattle’s infield hasn’t held up its end of the bargain. It’s not just about fielding percentage either — defensive metrics like Outs Above Average show the Mariners are giving up more outs than they should be, and in close games, those extra outs make all the difference. Until they clean it up with the gloves, they’ll keep making things harder than they need to be.

The bullpen has been overworked and can't strike anyone out

In today’s game, a shutdown bullpen needs one key ingredient: strikeouts. Unfortunately, the Mariners’ relievers haven’t gotten the memo. Their bullpen owns the worst strikeout rate in the league at just 7.10 K/9.

This is a serious problem. Strikeouts are the cleanest, safest way to get outs, especially in high-leverage situations. When the ball is constantly in play, weird things happen — bloops fall in, grounders find holes, errors become more costly. Without swing-and-miss stuff, the Mariners’ bullpen is living on the edge every single night.

They’ve had to rely on weak contact and good positioning, which isn’t always sustainable, especially when the defense behind them isn’t reliable. There’s talent in the pen, no doubt, but unless they start missing more bats, late-inning leads are going to continue to feel very shaky.