When there’s been an opportunity this offseason to talk about an under-the-radar prospect most likely to break out, the Mariners have used it to tout righthander Juan Then.
That wasn’t the case when Then was part of the Mariners’ alternate training site camp.
But even without a minor league season, the 6-foot-1, 175-pound Then showed up a few months later for instructional league and suddenly was touching 100 mph—up from 92-96—and his slider had progressed. Those improvements complemented what the Mariners had already liked in Then’s changeup.
“By the time we left Arizona (his slider) was a plus pitch,” Mariners farm director Andy McKay said. “He was like 95-99 (mph) every time with a really good slider. That was great to see.”
That made it an easy decision to add Then to the 40-man roster, protecting him from the Rule 5 draft.
And it’s not like he wasn’t performing. Across three levels in 2019, including three starts with Low-A West Virginia, Then had a 2.98 ERA in 48.1 innings with two home runs allowed, 48 strikeouts and 13 walks.
The Mariners initially signed Then as an international free agent out of the Dominican Republic in 2016 before trading him a little over a year later to the Yankees, along with two other prospects. The Mariners then brought Then back near the 2019 trade deadline for Edwin Encarnacion.
“There is so much development in front of him,” Mariners general manager Jerry Dipoto said. “Of all our 40-man players, he is the guy who has the chance to make the biggest step forward in ’21 after he already took maybe the biggest step forward in 2020.
“But now that he is on the 40-man roster and the clock is ticking with (minor league) options, we would anticipate a pretty quick ascent for Juan. I don’t anticipate that in 2021, but I think by this time next year I think you’ll be quite surprised by the physicality of his stuff and how quickly he could come.”
— The Mariners are bringing a haul of their top prospects with them to spring training in Peoria, Ariz., as non-roster invites to go along with their 40-man roster.
Some of those include outfielders Jarred Kelenic and Julio Rodriguez, catcher Cal Raleigh and righthander Logan Gilbert. It’s likely all of them except Rodriguez make their major league debuts at some point in 2021.
— Some of the notable prospects not invited were righthander George Kirby, their 2019 first-round pick, and shortstop Noelvi Marte. Both are expected to begin the season with one of the Mariners’ low minor league affiliates.