He's going to be 35. Two of his last four years were bad to meh. The other two were good to great. Is that worth a $15 million dice roll? If everybody is healthy, there is the same kind of a log jam next year that Zimmerman's injury has hid.

The Span option is a no-brainer.
The Soriano option is close to a no-brainer.

The LaRoche option? Tough call.

Over the last 4 seasons, he's made:

2011 - $7 million
2012 - $8 million
2013 - $10 million
2014 - $12 million

According to Fangraphs, who convert wins to dollars at a market rate, he's been worth:

2011 - $0
2012 - $15 million
2013 - $2.7 million
2014 - $9.4 million (and counting)

So they got decent value out of the contract. What are the odds that next year looks like 2013 v. 2014? I don't think it's an easy answer. That money could go to somebody else's long term extension. He's lost a step in the field. But I still think he'd be a productive hitter, but $15 million would make him the second highest paid position player behind Werth.