Jon Heyman's new Inside Baseball column contains a tidbit on the Pirates:
They have fielded offers on all seven of their players who have a year to go before free agency, so that also includes Neil Walker as well as Melancon and Pedro Alvarez ... They have thought about locking up Francisco Cervelli, who emerged as a star.
The other four players with a year to go before free agency are Charlie Morton, Michael Morse, Chris Stewart and Cervelli. It isn't news that they'd at least consider trading Walker, Melancon or Alvarez, and it's not surprising that they'd consider dealing Morton or Morse if the right offer came along. Morton is, in my opinion, unlikely to be dealt; he wouldn't have a ton of trade value at this point, he's a reasonable candidate to bounce back a bit next year, and the Pirates need pitching. My guess is that the Pirates would only trade Morse (who doesn't have a ton of value right now either, despite his decent performance for the Bucs down the stretch) if they acquired another first baseman.
That leaves Stewart and Cervelli. Trading Stewart might be possible, given that the Pirates have another credible catcher in Elias Diaz. Depth at the catcher position is important, though, and it's hard to see the Bucs getting an offer that makes trading Stewart worthwhile, given that he's cheap and provides good value in pitch-framing and working with pitchers for which teams haven't shown much willingness to pay heavily.
As a fan, I'd be thrilled about a Cervelli extension, but I'm not sure it's actually the right move for the Pirates, given that Cervelli is about to turn 30 and they already have him controlled through next year. There's also the fact that the Pirates have now acquired three good or very good catchers (Cervelli, Stewart and Russell Martin) for pennies on the dollar; I'm not sure how likely it is that they can do it again, but the possibility that they can is at least worth considering. There's also the chance that Diaz could emerge in 2016 as a legitimate big-league starter.
Cervelli has "only" made a few million dollars in his career, so maybe the Bucs could offer him, say, a cheap three-year deal and hope he leaps at the chance to ensure long-term financial security for himself. (I'm not sure there would be much point in extending Cervelli any further than that.) He's projected to make only $2.5 million next year, so taking that as a starting point and adding a couple seasons at $10 million each would come out to $22.5 million. That would seem reasonable to me, but I'm not sure it would be a good risk to go much beyond it.