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Series Preview: Mariners (20-20) at Red Sox (22-19)

The Mariners head to Boston to face an up-and-down Red Sox ballclub.

St. Louis Cardinals v Boston Red Sox Photo by Billie Weiss/Boston Red Sox/Getty Images

The Mariners head to Yawkey Way this week to face the Red Sox, who they haven’t yet faced this year and won’t see again until the last day of July. After locking down the series against Detroit with an offensive burst on Friday and another great start from Bryce Miller on Saturday, the M’s collaborated with the Tigers on a real flop of a game yesterday. A series win in Boston would put the team one game above .500; a sweep would put them three games over for the first time in 2023. Starting pitching has been exciting for both Boston and Seattle this last week, with Miller’s record-setting numbers so far, Chris Sale throwing a gem, and James Paxton taking the major league field again after more than two years away (!). Unfortunately, none of those three are scheduled to pitch this series, so we’ll have to turn our attention elsewhere.

At a Glance

Mariners Red Sox
Mariners Red Sox
Game 1 Monday, May 15 | 4:10 pm
RHP George Kirby RHP Tanner Houck
49% 51%
Game 2 Tuesday, May 16 | 4:10 pm
RHP Luis Castillo RHP Nick Pivetta
56% 44%
Game 3 Wednesday, May 17 | 4:10 pm
LHP Marco Gonzales RHP Brayan Bello
40% 60%
*Game odds courtesy of FanGraphs

Team Overview

Overview Red Sox Mariners Edge
Overview Red Sox Mariners Edge
Batting (wRC+) 111 (3rd in AL) 93 (10th in AL) Red Sox
Fielding (OAA) -5 (12th) 10 (1st) Mariners
Starting Pitching (FIP-) 118 (13th) 79 (2nd) Mariners
Bullpen (FIP-) 95 (8th) 75 (1st) Mariners

The Boston Red Sox suffer from being a fine team in the winningest division in baseball. Their 22-19 record would put them second in any other AL division, but in the East those are last place numbers. What was a two-star team in 2022 (Xander Bogaerts and Rafael Devers) is down to a one-star team this year, with Bogaerts leaving for the Dodgers in free agency. Devers signed a 10-year extension in the offseason and is joined by a new and returning crew that’s been offensively great. The Red Sox are third in baseball in runs (226) and 4th in team wRC+ (113), even without key players including shortstop Trevor Story (out till late in the season after UCL surgery) and center fielder Adam Duvall (out until June with a wrist fracture).

The pitching, then, is what’s held Boston back. The team is 23rd in team FIP (4.57) and has given up only 11 fewer runs than they’ve scored (remember that was third in baseball). The rotation has been the weakest link, with all the regular starters putting up poor numbers and no strong candidates for reinforcement from the minors. Headliner offseason bullpen signing Kenley Jansen has been an opposite story until recently: he had a 90% save rate until he blew two consecutive saves on Friday and Saturday. Boston was red hot to start the month of May, carrying a 7-game win streak, but these pitching meltdowns have lost them several recent games; they come into this series on the heels of a sweep at the hands of the basement-dwelling Cardinals.

Red Sox Lineup

Player Position Bats PA K% BB% ISO wRC+
Player Position Bats PA K% BB% ISO wRC+
Alex Verdugo RF L 172 14.0% 8.1% 0.188 133
Masataka Yoshida LF L 146 10.3% 10.3% 0.197 145
Justin Turner DH R 173 13.9% 11.6% 0.122 112
Rafael Devers 3B L 167 20.4% 6.0% 0.281 115
Jarren Duran CF L 95 24.2% 7.4% 0.214 165
Triston Casas 1B L 124 25.8% 16.9% 0.188 92
Enrique Hernández SS R 154 20.8% 7.1% 0.113 72
Enmanuel Valdez 2B L 47 25.5% 2.1% 0.200 130
Connor Wong C R 91 29.7% 5.5% 0.214 97

Boston fields a strong lineup, and the hot spots aren’t necessarily where you’d expect if you haven’t been following the team so far! Number two prospect Triston Casas and veteran infielder/outfielder Enrique Hernández are underperforming expectations (Hernández for the second year in a row) and playing below replacement level. Those are significant holes in the lineup, but aren’t stopping the team from being a top-five offense in baseball. With Hernández playing shortstop in Story’s absence and Duvall injured, Jarren Duran is up from the minors to play center field and is making an impressive showing. Though his 158 wRC+ will certainly regress, he’s already racked up 1.4 fWAR and combines with a finally-breaking-out Alex Verdugo and newly acquired Masataka Yoshida for a killer outfield that’s averaging 143 wRC+. You may remember Masataka Yoshida from Team Japan in the WBC and moments like this one that put him on the national radar before his transition from Japan to MLB was complete. After a real struggle in his first two weeks, Yoshida has been tearing it up and is back to being the favorite (albeit far too early in the season for meaningful odds) for AL Rookie of the Year.

Probable Pitchers

Updated Stuff+ Explainer

MLB: Boston Red Sox at Philadelphia Phillies Kyle Ross-USA TODAY Sports

RHP Tanner Houck

37 2/3 20.6% 8.8% 11.8% 50.0% 5.26 4.03
Pitch Frequency Velocity Stuff+ Whiff+ BIP+ xwOBA
Four-seam 13.2% 93.9 100
Sinker 23.2% 93.6 111 116 110 0.268
Cutter 19.7% 91.7 79 96 103 0.311
Splitter 12.5% 87.5 80
Slider 31.5% 83.8 114 97 103 0.312

Straddling that line between high-leverage reliever and solid starter, Tanner Houck has spent all of this year in the rotation after making 28 appearances out of the bullpen last season. With a unique, side-arm delivery that imparts tons of horizontal movement on his pitches, he’s a menace against right-handed batters. Against lefties, he’s a lot more hittable and he’s introduced a cutter to his repertoire in an attempt to even out his platoon splits. So far, that hasn’t worked out the way he’s wanted with a bigger split than ever. His overall strikeout rate has also fallen to just over 20%, a pretty significant fall from the 30% rate he ran during his rookie campaign.

RHP Nick Pivetta

34 2/3 22.8% 9.5% 18.2% 34.0% 6.23 5.77
Pitch Frequency Velocity Stuff+ Whiff+ BIP+ xwOBA
Four-seam 50.1% 93.8 109 106 58 0.401
Curveball 29.6% 78.5 111 73 64 0.393
Slider 15.3% 86.2 109 88 74 0.321

Nick Pivetta has enjoyed a bit of a resurgence in Boston after flaming out in Philadelphia a few years ago. He’s always possessed a pair of strong breaking balls but his fastball has been inconsistent and he’s lacked a offspeed pitch to round out his repertoire. When his heater is working, it’ll generate plenty of whiffs at the top of the zone, but his command is spotty enough that the pitch will leak down in the zone pretty often leading to tons of loud contact. He’s dabbled with adding a cutter and changeup to his arsenal but neither pitch is ready for primetime which means he’s left to the whims of his fastball.

RHP Brayan Bello

23 1/3 22.9% 6.7% 29.4% 62.5% 5.01 5.05
Pitch Frequency Velocity Stuff+ Whiff+ BIP+ xwOBA
Four-seam 18.6% 96.1 84
Sinker 38.4% 95.6 97 71 79 0.409
Changeup 20.9% 87.7 83 161 75 0.168
Slider 22.1% 85.2 109 84 107 0.445

Brayan Bello seemingly has all the tools he needs to develop into a frontline starter for the Red Sox but has been unable to put it all together through parts of two seasons in the big leagues. A diving sinker, and nasty changeup, and a slider with tons of drop help him generate tons of contact on the ground. Unfortunately, he’s also prone to allowing really hard contact if he leaves any of his pitches up in the zone. He’s gotten some of his command issues worked out this year, but that’s meant he’s locating his pitches in the zone more often, leading to more contact. He lacks the pinpoint control to be able to stay on the edges of the strike zone and that remains his one remaining development hurdle.

The Big Picture:

The AL West

Team W-L W% Games Behind Recent Form
Team W-L W% Games Behind Recent Form
Rangers 25-15 0.625 -- W-W-L-W-W
Angels 21-20 0.512 4.0 L-L-W-L-L
Astros 21-19 0.525 4.5 W-W-W-L-W
Mariners 20-20 0.500 5.0 W-L-W-W-L
Athletics 9-33 0.214 17.0 L-L-W-L-W

The AL West standings remain stable as the Rangers keep winning and the A’s keep losing, this time against each other! After taking three of four in Oakland, the Rangers will host the Braves this week while the Athletics take on the Diamondbacks. The Angels lost their series against the Guardians and now head to Baltimore, while Houston plays one Chicago team (the Cubs) after taking two of three from the other (the White Sox).