He's worth owning regardless of his role, as his K/WHIP numbers are significant enough to have an impact, even in a relief role. If he's closing, his value skyrockets!
Whether or not he permanently takes the job is something only Mike Scioscia can answer. But I'd want KRod over Kolb this week or any other if they're both closing. No knock on Kolb, who's doing a great job. But KRod would be my choice.