Like it or not, they would not go that far over slot money. If he fell that far, he'd be falling farther still.
And frankly, I'm not sure I ever like investing that much in a pitcher, no matter who he is, until I know his arm can handle the workload. How many top talent pitchers drop down because of arm trouble when they try to get moved up to the full-MLB-season level? 33%? 50%?