First it was because he struck out too much until he inconveniently cut back his k-rate to a more respectful figure in AAA -- a lower k-rate then what Wil Myers produced in AAA this season in his second-time-around at that level.
Then, it was so he could gain experience playing for a winner in the playoffs because we all know how critical for guys to "learn" to win -- that whole out-scoring the opponent is a foreign notion to athletes who have been competing since the age of 7. But Oklahoma inconveniently got swept.
All along it's been some vague notion of safeguarding guys on the 40-man roster even though there's a lot of dead and near-dead wood on that roster and a whole lot of top prospects who don't need to be protected yet because they don't yet qualify for the Rule 5 draft.
So what is the next excuse? Probably the one that's been the real one all along -- money. The Astros, with the league's stingiest payroll, don't want to start the clock running on Springer, and if that is the real one, we may not see Springer until June, a pretty depressing prospect.
I'm tired of the excuses. They share in common a cost: player development. Springer has unbelievable strengths as a player - speed, athleticism, strength, focus and effort. He also has areas that need improvement. Exposing him now to big league pitching when there's no pressure of winning is a good thing. There's a real chance here for Springer to learn how MLB pitching differs so he can have an even better focus on what to work on during the off-season and next Spring. There's a chance for him to begin the adaptation process so next year isn't such an abrupt change. In short, there's a chance to accelerate his already rapid development.
The cost of foregoing that chance is higher than protecting a fringe guy who might otherwise make the 40-man roster.