According to Rob Biertempfel of TribLive Sports, "there is mutual interest between the Pirates and free agent pitcher J.A. Happ...but the sides have not yet formally discussed a contract offer."
This season, Happ pitched 172 innings and posted an ERA of 3.61 along with an FIP of 3.41; and with the Pirates, he was much better. After being acquired at the July 31st trade deadline, Happ became elite. His K/9 jumped from 7.90 to 9.81; his BB/9 plummeted from 2.35 to 1.85; and his ERA and FIP both dropped significantly, to 1.85 and 2.19, respectively.
While the Pirates would like to have him back, this is Happ's first time as a free agent, and is likely his only shot at a major payday. He wasn't eligible to receive a qualifying offer, and as such there won't be a penalty for the team that eventually signs him to a contract.
Dave Cameron of FanGraphs projected that Happ will receive a three year deal at $24 million, while the crowd sourced projection was for the same total length, but at $33 million. Teams might be reluctant to offer Happ three years, as he's already 33, and this past season was his best since 2009.