The month of September is here and man are we behind in ranking our Top 40 Mariners prospects. Thankfully, we find ourselves into the Top 20 and this portion of our list is filled with future big leaguers.
Before we crown the 16th to 20th best prospects in the Mariners system, let’s get our standard disclaimer out of the way: these ranks are not expert level ranks. We are using statistics, second-hand knowledge, and grainy video provided by MILB.TV.
In other words, these ranks are mostly about the fun that comes with ranking any group of players. With all that in mind, let’s get started.
20. Juan Then
Acquired in the Edwin Encarnacion trade, there was a running joke that Seattle traded their best trade chip for a player they had just two years. Then reports surfaced that Jerry Dipoto left “more on the table” for Encarnacion to save money. Maybe he did but pretending that Then isn’t a solid prospect is insane.
A 19-year-old RHP, Juan Then is a pitcher who is more advanced than most his age. He has above-average command of his fastball, which shows good arm side run and sits in the low 90’s and has touched 95 mph in shorter stints.
The command allows the pitch to play up, as it does with the changeup. The pitch is thrown with good arm speed and has good fade as well. The curveball shows good depth and has a decent chance to become a third above-average offering.
At 6’2″, 160 lbs., there is still a good chance Then can add good muscle to his frame and kick up his velocity another notch. In 48.1 innings across three levels, Then has posted 48 strikeouts and a 0.95 WHIP.
2020 will be a big year for Then, who could make it up to AA Arkansas if all goes right. He has a high floor of a middle reliever and a ceiling of a #4 starter, meaning he should be a big leaguer in 3 years.
19. Ricardo Sanchez
One of the forgotten members of the loaded Arkansas Travellers, Ricardo Sanchez had a really nice season after he was acquired for cash last winter. The LHP was having a great season until he hit a wall in his last 3 starts, surrendering 17 runs in 13 innings.
Sanchez has a chance at 3 average offerings with average command. All three pitches will flash plus at times but usually sit squarely in the 50-grade range. There is a possibility that a move to a bullpen could help his stuff play up as his fastball has hit 95 MPH in shorter stints. The changeup gives him a chance against RHH as well.
Sanchez will likely start 2020 in Tacoma if he can survive the roster crunch this winter. He doesn’t have the highest upside, so he isn’t a lock to stay on the 40-man this winter. There is a chance he can be a solid #5 starting going forward.
18. Ljay Newsome
Perhaps the highest riser of any prospect on our list, Ljay Newsome is one of the best stories in the organization. A soft-tossing righty with no MLB prospects at the end of last season has planted himself squarely on the path to the big leagues. How did he do it?
Well, the Mariners helped him. He was invited to what the Mariners call “Gas Camp”, an off-season program designed to increase velocity. It worked and Newsome went from a guy who occasionally hit 87 MPH to one who sits 89-91 and can touch 93.
An impressive achievement and one that didn’t cost Newsome a point off his best skill: his control. Newsome doesn’t walk people. In 155 innings this season, he has walked 17 batters. That is insane. He also added 169 strikeouts in those innings, giving him a beyond elite K: BB ratio.
Stuff-wise, Newsome still has a long way to go. The fastball is still just average and the changeup is inconsistent. The curveball is also a work in progress. The slider is his best offering, showing good life and is thrown in all shapes and forms.
Newsome survives on smarts and pitchability to get outs and his stuff is now good enough to make him a viable big leaguer. Rather that is in the rotation or as a mutli-inning reliever/opener, be should know sometime next season.
The tertiary piece of the big James Paxton for Justus Sheffield trade, Thompson-Williams was one of the most interesting prospects entering this season. He was coming off a 20/20 season in High-A and a recent swing change helped him tap into his natural power.
But it was a struggle in 2019 and DTW finished with a putrid .689 OPS, spending the entire season in AA Arkansas. The biggest issues were with strikeouts, he racked up 150+ in 430 PAs. But the athleticism and bat speed are still evident.
Thompson-Williams is Rule 5 eligible this winter, so he will need to be added to the 40-man unless Seattle thinks he can slide through. There is still a high likelihood that he can bring 5 average or better tools to the field, though his upside may be capped as a 4th outfielder.
The tools are too loud to give up on and a solid first half of 2020 could rocket him into the top 10 a year from now.
The second-round pick of the 2019 MLB Draft, we could be too low on Williamson. The 6’6″, 210 lb lefty has a chance at two, plus offerings, including a 95 MPH heater from the left side. He backs it up with a sweeping slider that is already an above-average, 55-grade pitch with the potential to increase a full grade.
After being drafted out of TCU, Williamson got a taste of pro ball by throwing 15.1 innings in Everrett. Things went pretty well as he posted a 2.35 ERA with 25 strikeouts and just 5 walks. Thanks to his frame, Williamson creates angles, making him tough to square up and he actually has room to grow on the 210 lbs frame.
It isn’t out of the realm of possibility we look up in a year and see Williamson with 4 above-average or better offerings. The curveball and changeup both need work but are in no way lost causes going forward.
Williamson’s command will need to improve, but he is a good athlete and has a fairly repeatable delivery. Thanks to his size and stuff, it isn’t hard to see a little James Paxton in the lefty and a candidate to be in the Mariners Top 5 this time next season.