On comp for Triston Casas might be Seattle first baseman Evan White, who in November 2019 signed a six-year, $24 million extension having never played above Double A.
White, who was 23 years old, was ranked in the 50-60 range on the following year's Top 100 prospect lists. Casas, who turns 23 in January, entered this season ranked No. 19, No. 16 and No. 44 at the major services.
White was coming off a season with a 132 wRC+ at Double A Arkansas while Casas is coming off a season of a 127 wRC+ at Triple A Worcester before his respectable debut with the Red Sox. Their career minor league lines:
EW 262 G, 1131 PA, .288/.356/.477/.833
TC 284 G, 1210 PA, .269/.374/.485/.858
White was the 17th pick of the 2017 draft out of college while Casas was the 26th pick of the 2018 draft out of high school. White, at 6-3, 219 pounds, bats right but throws left while Casas, at 6-4, 252 pounds, bats left and throws right.
The White extension has not turned out well for the Mariners as the 2020 Gold Glove winner has posted a negative 0.6 fWAR/bWAR in 84 MLB games.
Therein lies the risk in signing a young player to an extension. Casas may have All Star potential but fans should be prepared for a wide range of outcomes.