The most famously bearded relief pitcher in Giants history threw another session off a mound on Monday, but that wasn’t the most interesting part.

It was the guests in attendance.

Giants pitching coach Dave Righetti stood in the batter’s box for most of the session, held at the University of San Francisco, a source tells CSN Bay Area. Giants bullpen catcher Billy Hayes caught Wilson as well.

Another source confirmed that both Giants coaches were in attendance to view Wilson, who looked impressive and game ready 15 months after having Tommy John surgery to reconstruct his right elbow.

Wilson remains a free agent; the Giants have no agreement or understanding in place with the three-time All-Star right-hander. Righetti and Hayes were there as a personal courtesy, according to sources.

“We want to keep in touch with his progress,” Giants vice president Bobby Evans said. “He’s a Giant through and through. So we want to stay involved.”

Righetti declined comment.

Wilson had terrific stuff, according to a source who saw him pitch. There wasn't a radar gun on him but was estimated to top out at 94 mph with movement on his cutter. He showed good feel for a changeup, too.

The Giants and Wilson had a falling out after the club non-tendered him last winter; the club would have been forced to guarantee him a minimum of $6.8 million through arbitration if they had tendered him a contract.