Excellent closers are not easy to find at a low cost.
I think Houck has a great profile to be a top closer, next year. I like him better than Iglesias or Hand and he'll be $10-14M cheaper.
Whitlock looks like he could be a very good SP'er and can get through the 3rd time through more easily than Houck, but having a RP'er that can go 2-3 innings is a huge asset in an era where starters rarely go 5 or 6 innings.
Again, I'm fine, if we use Whitlock as a starter, especially if we can trade for Trivino or the like, but until we do, I'm thinking I'd rather us sign Stroman, Glausman, Ray or Rodon than Igesias or Hand. (Matz > Hand, too.)