Diamondbacks Non-Tender Welington Castillo, Rubby De La Rosa

The Diamondbacks decided not to tender arbitration contracts to catcher Welington Castillo and righty Rubby De La Rosa, per a team announcement. The decision on Castillo, in particular, rates as a surprise; both will be available to the highest bidder on the open market.

Castillo had been projected by MLBTR and contributor Matt Swartz to earn a fairly hefty $5.9MM in his final season of control. But in this market, with more teams seemingly in need of catching than there are serviceable backstops to go around, that seemed plenty reasonable.

After all, Castillo is still just 29 years of age and provided the D-Backs with 457 plate appearances of .264/.322/.423 hitting last year, while swatting 14 home runs. That was slightly below a league-average rate of production for a hitter, but is quite useful for a catcher. And Castillo had shown some real upside just a season before, when he popped 17 long balls and OPS’ed .813 over 303 plate appearances following his mid-season acquisition by the Snakes.

Of course, offense isn’t everything, particularly for the catching position. Castillo rated as a slightly below-average framer by StatCorner’s measure in 2016, though he was right at par the season prior. In the view of Baseball Prospectus, though, he was rather terrible at gaining strikes for his pitchers last year.

On the surface, even with the questions about his ability to win the corners for a team’s staff, it might have seemed that Castillo would at least have held trade appeal. Surely, though, that possibility was explored by Arizona before it finalized its course. From the organization’s perspective, it can roll the dice that Chris Herrmann (at a projected $1MM arb salary) will reprise his surprising run from 2016. And it’ll look to help nurture its rotation back to health with a steady hand in a reserve role, as the D-Backs have reportedly agreed to terms with free agent Jeff Mathis, That duo figures to cost a fair sight less than Castillo would have alone.

De La Rosa, whose elbow health is in question, was projected at a $3.0MM tab. That was an amply reasonable amount for his talent, particularly considering that there’s another season of control to go, but the team may not have been encouraged by the medical signals it received.

Last we checked in, the 27-year-old was undergoing stem cell therapy in an effort to avoid Tommy John surgery. He has previously undergone a UCL replacement in his career, and at this point, a repeat procedure surely would’ve caused him to miss all of the 2017 season. In that event, Arizona would’ve been required to promise him the same rate of pay both for 2017 and 2018, all in the hopes that he’d return (and return to form) in the second of those two years.

That being said, it’s tough to give up on a pitcher of De La Rosa’s promise. He had turned in 50 2/3 innings of 4.26 ERA pitching in 2016, and struggled with the long ball, but did post a strong 9.6 K/9 rate to go with his 3.6 BB/9. Some ERA estimators believed he had been a bit unfortunate, as he ended the year with a 3.85 FIP and 3.86 SIERA. De La Rosa brings a mid-nineties heater to the table, and will be an interesting bounceback candidate.