Flaherty would also require a 40-man roster move.
At this point, clearing spaces on the 40-man is seriously non-trivial. Yeah, Eickhoff could be moved to the 60-day, but would then be unavailable until about Memorial Day. That's not a trivial decision.
Beyond that? The next move appears to be to DFA Cameron Rupp. After that? If you want to propose adding a current non-roster player to the bench or the pitching staff - do us a favor and identify who you would release, or expose to waivers, to make room for that player.
Valentin, Florimon, Quinn, Lively, Eflin have the inside track on 25-man roster positions because: 1) they're not clearly better or worse than the various non-roster candidates; and 2) the organization doesn't have to sacrifice a prospect to make room for them.
You want Eshelman, Hutchison, Flaherty? To be considered, any of them has to be clearly better than on-roster alternatives... and enough better as to justify losing a prospect to a waiver claim.
Because of the roster issues, this isn't simply about "Who would be better for the month of April?" These decisions have long-term implications, that the GM needs to consider. We shouldn't lose sight of that.