I know from sooooo many spring trainings that what happens during these brief few weeks of ramp-up almost never translates into what happens during the season. And yet, I find myself relying on what happens to justify opinions on who makes the roster and who gets sent down, opinions on how far a minor leaguer is likely to go in the long run, but also more rational (in my mind) selections of who to watch in the upcoming season, especially in the minor leagues.
I see guys drafted, then they disappear from view in Sarasota or even in the lower levels, and then even when they get to the AA and then AAA level are facing competition that may or may not be challenging them enough.
So seeing them perform in Spring Training, especially when they're set up against Major League opponents, and seeing their stats over time in these situations, really does inform me a lot, to see what might really be there.
Admittedly, I may be relying more on the eye test than stats tho.