Seattle Mariners Sleepers to Watch in 2021

In a division with the star-studded Angels and Astros and the ever-consistent Athletics, it's easy to overlook the Mariners and Rangers in the American League West. And while you may have good reasons to look past the Rangers, the Mariners have several intriguing fantasy players for the 2021 season that could be going a bit under-the-radar in your league.

I also like to come up with a list of players I think are overlooked coming into each season, and one thing stuck out to me more than anything else: many of them were Mariners. Seattle finished 27-33 in a shortened 2020 season, and FanGraphs has them projected for a third straight sub-.500 finish. However, I'd argue that the Mariners have significantly more upside than any other teams around their projected win total. They don't have a true star, but many of their players are more than capable-- significantly better than their lack of publicity would suggest.

If you don't know me, I'm Jeremy Frank. I run the Twitter account @MLBRandomStats where I tweet a lot about baseball stats. I'll be posting occasional articles for RotoBaller throughout the season when I have something interesting to write about. To start, here are five Seattle Mariners I really like, fantasy-wise and in general, for the 2021 MLB season.

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Dylan Moore

One of my favorite under-the-radar fantasy players in the sport is Dylan Moore. Moore brings a bit of everything to the table. For one, he adds a lot of flexibility to rosters, with 10 games played at second base, left field, and right field in 2020 despite the shortened season. While he looks to be slotted in to get most of his playing time as the second baseman for the M's this season, Moore's versatility gave him starts at first base, shortstop, third base, and center field in 2020, in addition to his main three positions.

Depending on your positional eligibility minimums, don't be surprised if Moore adds another position or two if the Mariners need him to move around. Moore was also one of just three American League players to rank in the top 30 percent in the MLB in expected wOBA, average exit velocity, and sprint speed. (Mike Trout and Teoscar Hernandez were the two others.) While the 138 wRC+ may seem like a small season fluke, he only slightly overperformed his solid .354 xwOBA. In addition, Moore stole 12 bases in 38 games last year, or a rate of 45 per 600 plate appearances.

Like I mentioned, Dylan Moore is one of my favorite under-the-radar guys going into this year. At an ADP of 155 and auction value of $7, he is one of the few guys you'll be able to find with a good bat, stolen base upside, and positional versatility in the middle rounds of your draft.

Ty France

Like Moore, France looks primed for a favorable lineup spot in the Mariners order-- and for good reason. In 43 games between the Padres and Mariners last year, the third baseman slashed .305/.368/.468. His expected batting average ranked in the top 15 percent of all MLB players, and his expected slugging was in the top quarter. Of all 203 players with 150+ PA in 2020, France ranked third in line drive rate at 30.8%, just behind only Jose Iglesias and Freddie Freeman.

His spring training OPS is Bonds-like, right around the 1.400 mark, with more homers in a few dozen spring plate appearances (5 in 41 PA) than he did all of last regular season (4 in 155 PA). He'll likely be the Mariners DH to start the season, but should have second base eligibility, and maybe third base, depending on the league. At a 303 ADP and $1 auction, France is a late-round steal if you can get him. Also, I feel obligated to mention his obscene .399/.477/.770 slash line with 27 HR and 89 RBI in 76 AAA games in 2019. Yeah, ballpark, but still.

Marco Gonzales

Sure, it was a shortened season, but no qualified pitcher in the last 120 years has ever posted a K/BB better than the 9.14 Gonzales had in 2020 while also allowing a lower slugging percentage than the .361 that the Mariners southpaw allowed. Yes, he has flaws: he doesn't get as many swings and misses as you'd hope, and his fastball velocity barely touches 90 on a good day; however, Gonzales limits hard contact (86.4 mph average exit velocity was in the 83rd percentile in 2020) and has elite control to go along with it.

His 3.10 ERA from 2020 was probably an overperformance, but FIP has him at 3.32, and Statcast's xERA has him at 3.76. He's one of sixteen pitchers to qualify for the ERA title in each of the last three seasons, and he beat the league average ERA and FIP in all three. He's not Kyle Hendricks, but he has shown to be a consistent innings-eater who should help your team more than he hurts it. Available in the 14th or 15th round in most 12-teamers, Gonzales is a solid option for teams that need reliable starting pitching, which I assume is pretty much all of them.

Yusei Kikuchi

If you just looked at the back of his baseball card, Kikuchi would seem undraftable in most fantasy leagues. As a 28-year-old rookie, the Japanese southpaw went 6-11 with a 5.46 ERA and just 116 strikeouts in 161.2 innings pitched. In a shortened sophomore year, Kikuchi went 2-4 with a 5.17 ERA. However, unlike his rookie year, he showed some flashes of what the Mariners hoped he would become when they signed him.

The left-hander struck out 47 guys in 47 innings, or a K/9 of exactly nine, and only allowed three home runs (0.6 HR/9) after surrendering 2.0 HR/9 in his first season. While ERA didn't recognize his improvement, nearly every other metric did. His FIP dropped from 5.71 to 3.30, his xERA (Statcast) dropped from 5.24 to 3.37, and he ranked in the top third of the league in xwOBA, opponent barrel rate, and whiff rate after ranking in the bottom third of the league in all three metrics a year prior. He stopped throwing his worst pitch, a curveball, instead throwing a much more effective cutter for the first time in the Majors.

His biggest improvement, I'd argue, was his ability to keep guys from putting the ball in the air; his opponents' average launch angle dropped from 12.3 degrees to 4.3 degrees, his ground ball rate increased from 44.8% to 52.8%, and his fly ball rate decreased from 21.9% to 16.5%. Kikuchi's ERA was bad in his rookie year because he couldn't strike guys out and he gave up homers more than just about anyone in the league; in his sophomore year, he increased his strikeout rate big time, got more grounders allowed significantly fewer homers, and his ERA was still bad. Don't expect that to continue.

If Kikuchi is able to keep the improvements he made going into last year, the rest of his stats will eventually follow with a bigger sample. His ADP is in the 110s, but depending on your league, it's possible he's around much later due to his ugly traditional stats in his only two MLB seasons.

Justus Sheffield

My runner-up for the American League Rookie of the Year (behind his teammate Kyle Lewis), Sheffield was massively overlooked by the voters, not getting even a third-place vote from any of the 30 writers. After a couple of sub-par starts at the beginning of the season, Sheffield tore it up over his last eight, going 4-1 with a 2.64 ERA in 47.2 IP.

The left-hander pitched at least five innings and allowed two or fewer runs in seven of those eight starts. His Statcast metrics leave some to be desired, and it's why he won't be an extremely high pick in this year's draft, but his expected wOBA, expected SLG, and walk rate were all at least average. He allowed just two home runs in 2020, to Anderson Tejada and Jo Adell of all players, and backed that up by finishing in the top 11 percent of the league in barrel rate.

Of the five, I think Sheffield is the biggest risk, but he could present some nice upside if he can get his strikeout numbers to where they were in the minors. His ADP is 108.3, which might be a bit early, but Sheffield is a really solid middle-round pick with good upside if you're willing to take a slight gamble on him.

The Mariners might still be a year or two from competing for a division title, but they do have valuable pieces right now that could be steals for your fantasy team. Moore is my personal favorite, but the other three could provide excellent bang for your buck if and when they fall to a favorable position in your draft.

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