It's hard to ever put any real stock in Spring Training results. After all, the level of competition varies from inning to inning and a lot of the top players are usually only giving it about 75% of their full effort. So it's hard to say that stats from Spring Training gave any indication that a player would be able to replicate that production when the real games started.
However, when it comes to these five players, there were some reasons to think that what they did in February and March could carry over into the regular season.