The extensions were risky, but they weren't any different than signing a free agent a bit above market value and that free agent not panning out or living up to their contract.
Riley's production being nowhere close to his extension numbers is what has hurt us the most. Strider is a pitcher so there was worry about his arm, but Strider makes WAY LESS than what a pitcher his value would be getting on open market. Strider can also be converted to a dominant reliever unless his arm completely explodes.
If Riley continued his production and then became so expensive that he couldn't be brought back, then the fanbase would be complaining about letting Freeman/Dansby walk again but this time with Riley. He's one I think AA felt he had to bring back because the southern fanbase would be outraged if Riley walked.
Riley getting much worse post-extension could not have been predicted this badly.
Murphy has been good just unlucky with injuries.