Tampa won games because their entire organization used statistics to get the maximum production out of their players. Their GM acquired players who could supplement others, and their manager followed through using the correct platoons and shifts that the information given to him suggested he do.
Mushroom is hot right now but I don't want him to take away at bats from Smoak. With a 3rd baseman who has a hard time throwing to first we need someone who can catch a ball thrown 4 feet from the target.
He was a dynamite reliever last year but it hasn't translated into good starting pitching. I think you either 1) let him stay on the roster as a reliever or 2) send him down and try to get him to work on his command.
Sanchez 1:1 K:B ratio is what's hurting him. If he can't find the plate teams won't feel the need to swing at his pitches. It's something he should be working on in the minors, not as a major league starter, IMO.
While I'm not the brass I would think that the reason why the former were given as much rope is because the organization wasn't worried about destroying their development at all. They are what they are. The later (especially Snider) were/are greater prospects that I'm sure the organization doesn't want to mess up developmentally. So sending them down was a way to get them more at bats in a less stressful environment and allow them to work on things where it wouldn't damage the major league team.
That being said, finding 1 year of a center fielder while Pompey started in AAA probably would have been a good idea.