They had him under control. I'm not even sure if he's arbitration eligible yet. If he wasn't, they could have paid him the league minimum or whatever they chose to pay him next year. Then, if they couldn't agree to terms, an arbitrator would determine his salary every year. By doing this, he likely will make the same, maybe a little less than he would have by forcing arbitration every year. Plus, it's all guaranteed now, so if he ends up having a less than stellar next couple of years, he still gets all the money. This happens all the time.
Nobody makes the huge money until they become a free agent. That's when the $20 million a year contract offers come pouring in.