40 in 40: Sam Tuivailala

The arrival of Sam Tuivailala in July 2018 was met with lukewarm reception; acquired from the Cardinals for relief prospect Seth Elledge, he arrived in Seattle with a career 4.16 FIP and a ground ball rate in the high-40% range. With Elledge dominating the Cal League at the time, some were sad to lose him, but Tuivailala immediately showed in his first appearance as a Mariner why Jerry Dipoto sought him:

Tui was effective in his first few outings, giving up just one run over 5.1 innings, and was poised to provide another bridge to Edwin Díaz until a fateful rundown on August 8th featuring perpetual heel Rougned Odor abruptly cut his season short (NSFW below):

rougned my dude your team was up by five runs here

He would rupture his Achilles at about the fifteen-second mark of the video, and had season-ending surgery just three days later. Although the initial hope was that he would be back by June, a couple of setbacks during his rehab assignments, including dead arm and shoulder tightness, kept him bouncing around Seattle’s farm for nearly two months until he was finally activated on July 15th. He stayed healthy the rest of the season, appearing in 23 games - as well as opening two - and posted a strong 2.35/3.13 ERA/FIP over 23 innings, allowing just a single home run and putting up a 28.3% K-rate in that span. Working mainly in the later innings, he turned in scoreless outings 19 out of 23 times, didn’t allow a run to score all of August, and only gave up multiple runs twice: once in his first appearance and again on September 21st.

Tuivailala throws decently hard, sitting at around 93-94 MPH on both his four-seam and two-seam fastballs. Those are accompanied by a hard slider that averages around 87, and he rounds out his repertoire with a high-70s/low-80s curve with big late break, as seen in the above .gif to Alex Bregman. In 2019, he did a solid job of mixing these four offerings:

Baseball Savant

Unlike Gerson Bautista, who Joe looked at on Monday, Tui showed a willingness to deploy both of his offspeed pitches in nearly any count, 3-0 being the lone exception. I’m especially impressed with his pitch mix on 1-1 counts; just over half of his pitches thrown were offspeed, and more often than not, he was able to get ahead in the count. He was also able to coax swinging strikes from all four of his pitches last year - the lowest rate was on his two-seam at 22.6%, and his curve managed a whopping 33.3%.

Alas, for all the positives that Tuivailala accomplished, a couple red flags remain. Command has been an occasional struggle for him throughout his big league career, and 2019’s 11.7% walk rate was a four-point jump from 2018. Last year, he threw about 57% of all his pitches out of the zone, six points higher than league average. He especially struggled throwing the curve for strikes despite the high whiff rate, with just 29% landing in the zone. Tui also allowed at least one walk in nine outings last year - in other words, nearly 40% of his appearances included a free pass.

Allowing just one home run in the 2019 offensive environment is undoubtedly impressive, as well, but there’s a case to be made that Tuivailala got especially lucky. His ground-ball rate last year was just 33.3%, which in turn resulted in a measly 3.4% HR/FB - pretty unsustainable given the amount of fly balls he allowed. xFIP was also much less kind to him than either ERA or FIP, giving him a mark of 5.07. There are some silver linings here, though - that 33.3% was the lowest ground ball mark of his career by ten points, so small sample weirdness may have played a part, much like how old friend Cory Gearrin saw his typically strong grounder rates dip heavily in brief stops with Oakland and Texas in 2018. Each of his offerings put up a weak-hit rate of at least 50%, he posted a pop-up rate of just over 10%, and allowed mostly weak-to-medium contact on fly balls, putting up an Under% (per Baseball Savant) of 35.2% - ten points better than league average. While it’s entirely possible that some big home run regression is on the way, it’s also reasonable to suggest that there’s underlying contact management happening. Or both can happen next year! Who knows!

Despite some question marks, Sam Tuivailala was undeniably one of Seattle’s best bullpen arms in the last ten weeks of the season, and is expected to slot in as a key middle reliever in 2020. After a grueling injury and rehab, he should be fully healthy provided Rougned Odor stays away. Although he’s out of options, he remains under team control through 2022, and stands a good chance at remaining an effective option during those three years - although those ground balls swinging back to their previous marks would be a big help in achieving that.