Poche and Sims had to be impossibly bad to get cut. Bell is currently a major play-the-contract beneficiary, as Gallo was last year.
Gallo had that 2 well-timed injuries. He played only 76 games and had 260 PAs. he was out 6/12 - 8/20, and before that, from 4/27 - 5/17. More or less, he had a month to get going, then a break, and another month to get going. I don't think it was the money that was keeping him from being cut.
I think they let Bell get 200 - 250 PAs before they pull the plug. He's at 128 now. End of May, maybe mid-June.