Happ has been one of the more durable pitchers in the game over the past couple of seasons. He has made 25 or more starts in five consecutive seasons. In 2018, he made 31 starts between the Yankees and Blue Jays and went 17-6 with a 3.65 ERA and a 193/51 strikeout-to-walk ratio.
This interest does not necessarily mean the Mets will indeed trade Syndergaard. Heyman notes that in any deal the Mets are asking for multiple pieces that will make an immediate impact at the big league level.
If that lofty asking price is met and the Mets do indeed move the big right-hander, they will certainly have some big shoes to fill at the top of that rotation.