Mets could be building a super-pen with addition of Devin Williams; could Edwin Diaz join him?

Signing Devin Williams is a major offseason W for the Mets, who checked another significant box Monday night by adding one of the game’s best closers to a bullpen that very much remains a work in progress.

Williams on his own is a solid building block, but that doesn’t seem to be the end game here. The Mets are thinking bigger, and adding Williams on a three-year deal worth $51 million, as a source confirmed Monday, is only the start of another attempt by president of baseball operations David Stearns to create the super-pen he failed to successfully assemble at last season’s trade deadline.

The Mets still have Edwin Diaz in their sights, and the idea of pairing him with Williams — who apparently is fine taking over the setup role if it comes to that — would be the early coup of the off