I feel like this one deserves its own thread as a very odd situation. The Mariners have signed prospect Evan White, who played in the Texas League this past year, to a 6 year, $24M deal with three club options after. He can max out at $55.5 million if all the options are picked up. I wonder if other teams might copy this in years to come? Maybe the Cards would do so with some of their prospects?
Yes, this is maybe unprecedented (or at least very rare) for a player who had gone through the draft. He is not yet even on the 40-man roster. It would be similar to if the Cards locked up Dylan Carlson long-term now.
On the part of the M’s, this may be a preemptive move to head off any changes to arbitration eligibility and salaries in the next CBA that would represent concessions to the players.
As an aside, a number of Cubans have gotten long-term deals to sign while still minor leaguers, but their situations were different as they were not already under team control. (The Cards had one in Aledmys Diaz, for example.)