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Three Mariners prospects whose outlooks have risen or fallen most in the 2021 season

It’s awfully hard to find disappointments in the Mariners organization this season

It has been a rather good year on the whole for the Seattle Mariners farm system. Several top prospects debuted, including Taylor Trammell, Jarred Kelenic, Logan Gilbert, and Cal Raleigh. We’ve seen full seasons from several players who had yet to put them together stateside, and have gotten encouraging development from Noelvi Marte, George Kirby, Sam Carlson, Brandon Williamson, and several others. Also, **gestures in the direction of literally everything Julio Rodríguez has done**. Even the things that have been mild letdowns have not, knock on wood, been entirely crushing or necessarily lasting issues, including Emerson Hancock’s abbreviated season, or injuries slowing early breakout Adam Macko and low minors speedster Jonatan Clase.

Still, at least a few prospects particularly have stood out, as the minor league season (save for Triple-A) rounds into the final two weeks of play, and we wanted to highlight them. Below are three players who have most risen in our estimation compared to the season’s outset, as well as three who fell furthest. Keep in mind this is based on change in expectation going forward, so while Julio and Kirby are perhaps the two most impressive prospects in the system right now, we already had lofty belief in their abilities.


RHP Matt Brash (Double-A Arkansas Travelers)
Season Totals (A+ & AA): 18 G, 86.1 IP, 2.08/3.14 ERA/FIP, 131-41 K-BB, 36.7% K%.

No player in Seattle’s system has improved his reputation outside the organization, and likely within it, than Matt Brash this year. Brash has been absolutely dominant this year, splitting his time almost equally between Everett and Arkansas, when he’s not headlining Pitching Ninja’s nightly reviews. Joe was psyched about Brash when Seattle acquired him as the PTBNL from the San Diego Padres in exchange for RHP Taylor Williams last trade deadline, but I think it’s fair to say this is above and beyond.

The 23 year old’s ceiling is tricky to measure, as Joe outlines in his tweet above. He’s now sitting 95-99, with one of the deadliest breaking balls in MiLB and easily the best breaker in the system. It’s elite metrically, measuring in north of 3000 RPMs on a regular basis, sitting in that 2900-range on most throws. He’s a Top-10 prospect in the system and quite possibly a Top-100 candidate for national outlets over this winter, though he may even have the chance to debut sooner than that.

It remains to be seen what Brash’s ultimate role will be in the organization. Jumping into the bullpen for the playoff push obviously wouldn’t staple his name into a bullpen role for 2022 and beyond, but as we’ve seen, high-leverage lockdown relievers aren’t easy to come by and Brash’s repertoire certainly fits that bill.

OF Cade Marlowe (High-A Everett AquaSox)
Season Totals (A & A+): 98 G, 453 PA .273/.364/.569, 24 HR, 21/29 SB/SBA, 12.1%/27.2% BB/K%.

In many ways Brash’s equivalent on the position player side, Marlowe has been earning kudos and recognition from several major national outlets, a reassuring sign for those who sometimes fear over-focus on Seattle’s system leads to overvaluation. While Marlowe is not likely the caliber of prospect Brash seems to be rising to, his physical and mechanical improvements are undeniable, and his results reflect that. With a swing geared for loft and a body well developed for strength and speed, Marlowe seems to have crafted himself into a dual-threat outfield prospect.

Joe wrote about Marlowe in depth over at Prospects Live, and I put together a scouting report on him recently at Baseball Prospectus, coming to similar conclusions: there’s more to Marlowe than simply being a tick older for the level, having turned 24 in late June.

Time will tell whether Marlowe will ultimately be a big league contributor for the Mariners or another organization in the future, but any time you can draft a player who debuts at the big league level at all in the 20th round, your scouting and player development departments deserve steak dinners.

OF Alberto Rodriguez (High-A Everett AquaSox)
Season Totals (A & A+): 95 G, 439 PA .292/.380/.477, 10 HR, 13/20 SB/SBA, 11.8%/22.1% BB/K%.

When Rodriguez was acquired in exchange for Taijuan Walker during the 2020 trade deadline, many felt the return was light for a starting pitcher having the year Walker was having. Fast-forward 13 months and it appears Dipoto may have done quite well in his haul from the Blue Jays.

Rodriguez put in the work this offseason, shedding some weight and getting noticeably stronger. The result has been a bit of a power surge without the sacrifice of his on-base skills. Quietly, Rodriguez has been one of the best hitters in the entire organization this season. His strikeout rate ranks among the best in the system and he’s tacked on a .477 clip to go along with it.

“A-Rod” just made his High-A Everett debuts and figures to jump back to that level next Spring as a 21-year-old. He and Marte represents two pillar figures in the “the following wave” coming through the system.


RHP Juan Then (High-A Everett AquaSox)
Season Totals (A+): 13 G, 50.1 IP, 6.62/5.86 ERA/FIP, 55-19, 24% K%.

It hasn’t been a disastrous year for Then by any measure, but I’m sure many were hoping to see a better performance than he’s posted to date. Armed with a high-90s fastball and a breaking ball that showed promise in 2019, Then was added to the 40-man roster following the 2020 campaign to protect him from the Rule 5 draft. Clearly, the Mariners front office thinks highly of him.

Then has been banged up this season. He missed about a month early on, but has regained his form and looked better of late. Then is striking out more batters than he ever has in his career at a 9.8 K/9 rate, but he’s also surrendering more hits, homers and walks than ever before. None of this is to be entirely unexpected from a 21-year-old at High-A. He’s still awfully advanced for his age and should continue to assimilate himself to greater competition in 2022. No reason to panic here.

3B/1B Tyler Keenan (High-A Everett AquaSox)
Season Totals (A+): 61 G, 258 PA, .187/.295/.341, 5 HR, 0/0 SB/SBA, 12.0%/37.4% BB/K%.

A fourth round pick in 2020, it’s been a tough start to Keenan’s career. The former Ole Miss Runnin’ Rebel is posting pretty troubling strikeout totals, and the power many hung their hat on in his scouting reports is yet to bear fruit. To his credit, Keenan has put his body in a much better position to potentially handle the rigors of third base long-term, but it’ll all be for naught should the bat not play up to it’s a potential.

A career .306 hitter in college, Keenan will be 23 next season and will likely repeat the High-A level. It’ll be an important year in his development as he won’t want to lag behind. Third base has rapidly become a position of depth inside the Mariners system with names like Ty France, Milkar Perez and potentially Marte in the cards at the position down the road. Not to mention the possibility to a free agent joining ranks.

OF Dom Thompson-Williams (Double-A Arkansas)
Season Totals (AA): 57 G, 208 PA, .188/.259/.317, 5 HR, 4/7 SB/SBA, 8.2%/33.7% BB/K%.

Thompson-Williams may be the cautious tale for Marlowe. Once a 20-20 guy himself, “D-TW” has suffered some hard luck over the past couple of years dealing with a devastating leg injury and the 2020 shutdown. He’s missed a lot of valuable reps over the last couple years.

It’s been a tough road for Thompson-Williams this season. The strikeout totals are high and he’s just not showing the speed or power he once did in the Yankees organization. D-TW will be 27 next season and is quickly approaching the end of his “prospect” status. That said, he’s still plenty young enough to make it. 2022 will likely be his third go at the Double-A level, just a hot streak and a phone call away from a cup of coffee.