Signing only one guy was obviously not enough. It left them vulnerable to ANY injury. If it wasn't to Giolito, it was to Whitlock, Houck or anyone else. At any point, one guy going down via injury or ineffectiveness would be disastrous for the rotation.
By artificially capping the budget, Henry truly f***ed this team. He might think he was being smart with his money, but I don't see it that way. He'd make much more if the team was successful.