Previewing the M’s bullpen

One of the major areas of concern for the Seattle Mariners heading into this off season was their bullpen. With a collective fWAR of 0.4 over 694.1 innings (Houston’s pen was worth 4 wins) in 2019, there is a lot of room for improvement heading into the 2020 season.

As a group, the relievers had an ERA of 4.77 and a FIP of 4.87 last year. Now a major part of that problem was injuries which led to 36 different relief pitchers taking the mound for Seattle; which would make you think there should be improvement once the pen gets more consistent usage and roles. But the guys I’m expecting to see on the roster weren’t that good last season either and there isn’t a lot of reason to expect major improvement for this group.

Seattle’s most valuable reliever last season was Austin Adam’s, and he’s starting this season on the 60-day injured list…so it’s unlikely we’ll be seeing him on the 26-man roster once he’s cleared to resume pitching. With the M’s planning on carrying 11-relievers on their 30-man roster, we’re only going to be taking a look at the guys I expect to see on their 26-man roster for the latter part of this season.


The 26-man bullpen

RHP Matt Magill

Magill came to Seattle last season via a trade with the Minnesota Twins for cash. The 30-year old saw 50.2 innings between the two clubs and finished the season with a 4.09 ERA and a FIP of 3.79. He saw a career high in strikeout rate; along with a career low in walk and batting average against.

The veteran did have some poor luck with balls in play last season, as opposing hitters had a BABIP of .324 against him. That was a pretty big reason for his ERA being that much higher than his FIP. If Seattle’s defense develops as expected, you should expect Magill’s BABIP and ERA to decrease…if his walk rate from 2019 is a sustainable development.

RHP Erik Swanson

At 25-years old, Swanson made his major league debut with the M’s last season. In 58 innings last season, his youth and inexperience was apparent. Despite a fairly high ground ball rate, low BABIP, and low walk rate; he had an ERA of 5.74 and a FIP of 5.96 last season. Those numbers were that high because the (now) 26-year old gave up 2.64 home runs per nine innings he was on the mound.

For this season to be a success, Swanson will have to cut the home run rate in half. And to do that, he’ll need to do a better job of of keeping pitches out of the middle of the plate.

RHP Taylor Williams

The 28-year old only appeared in 14.2 innings last season, but earned an ERA of 9.82 and a FIP of 3.90. Williams had an incredibly high BABIP of .438 against him last season, but that number makes a lot more sense when you look at the type of contact batters were getting off of him last season. Only 14.3% of contact was soft, while his medium and hard hit rates were at a high rate of 40.8% and 44.9% respectively. It’s hard for defenders to get into position to make a play on the ball when its hit consistently hard like that.

There really isn’t a lot in his short stint with Milwaukee last season that looks all that good. Hopefully the M’s can figure out a mix of his pitches that will help him, because his reliance on slider was a problem last season. William’s probably makes the 26-man roster because it’s a 60-game season with no minor league system for him to work on a mix of pitches that will allow him to better utilize his slider.


RHP Brandon Brennan

Brennan also made his major league debut last season, and he used his change-up to induce an ground balls in 55.2% of balls in play. Because of the rate of grounders, the 28-year old held batters to an average of .235 on balls put into play…but he still struggled with allowing runs as his FIP of 4.40 shows.

The major reason he was responsible for so many runs scoring was his dangerously high walk rate (12.2%). It put far too many batters on and his defense was unable to bail him out — even with the ground balls. Brennan will need to get his walk rate down heading into 2020, because there is almost no chance he’ll be able to maintain that ground ball rate for another season.

RHP Dan Altavilla

Altavilla is the most established member of the Mariners bullpen as he’s entering his fifth season with the club. Last season was not a good year for the veteran pitchers as he struggled to strand runners and with allowing walks — 2019 was the second straight season where he’s been over a 17% walk rate. He continues to have a sterling batting average against, but he let too many runners which led to an ERA of 5.52 and a FIP of 4.10.

With him allowing a home run every 0.61 per nine innings, and his ground ball rate increasing to 45.5% there is reason to be optimistic about him…if the 27-year old can get his walk rate under control.

LHP Taylor Guilbeau

Guilbeau only appeared in 12.1 innings for Seattle last year and posted a shiny ERA of 3.65. But don’t be fulled by the 27-year old’s low ERA as his strikeout rate is too low while his home run rate is a little too high. As a result, his FIP was a disconcerting 5.16 last year.

The good news is that he has a dangerous change up that he used to compliment his fastball. I’d like him to mix his slider in a little more as it’s got some promise and should make it harder for hitters to figure out which of his off speed pitches are coming in a pitchers count.


LHP Nestor Cortes

The 25-year old pitched in 66.2 innings for the New York Yankees last season. Cortes allowed 2.16 dingers per nine innings while also walking a slightly concerning 9.4% of batters faced; when you combine that with bad luck on balls in play it makes sense that he had an ERA of 5.67 with a FIP of 5.04.

The good news is that he was pretty good at stranding runners on base and inducing ground balls. If Cortes gets a little luckier with balls in play and reduces the number of homers allowed, he would be a very nice addition to the bullpen…as well as a potential piece to fill out the rest of the pen’s roles.

Season outlook

As this article was being written, the Mariners announced that Yoshihisa Hirano was placed on the injured list as he hasn’t reported for camp yet. This is a blow to the bullpen as they were going to need his arm to eat up innings..even in this shortened season.

There isn’t a lot of depth for the bullpen, and it got a lot thinner with Hirano going on the IL.

Another concern is the lack of left handed relievers on the M’s 60-man roster. With MLB’s new rules going into effect, the era of the LOOGY is dead…but it would still make sense to have some left handed relievers on hand in order to balance out the rotation and punish left handed line-ups.

While the 30-man roster will have 11 relief pitchers, I’m fully expecting to see Seattle whittle that down to six by the time the roster is down to 26. Bullpens are just so erratic from year to year that it makes more sense to give your young position players as many plate appearances and innings in the field as possible while rebuilding.