"Can't miss players" do not have a 1 in a hundred chance of hitting it big.
Nobody is asking to lock in Casas, now. There was some talk earlier, and he is an example of why you don't/shouldn't lock every promising prospect up long term.
The other aspect is how much are you paying them? Take Bello and KC, who seem like the most likely to be busts. Neither got superstar pay or even good star pay.
Remaining pay:
Bello: $6M, $8.5M, $16M, $19M then $1M buyout for 2030. That's $50M/4 remaining. What would Bello have gotten as a 26 year old FA coming off a 3 season with a 105 ERA+ and a 6.6 bWAR?
Campbell: 26:$2M, 27:$3M, 28:$4M, 29:$6M, 30:$9M, 31:$13M, 32:$16M, 33:$19M club option ($4M buyout), 34:$21M club option (no buyout)