He is currently the manager of the Hi-A Carolina League Lynchburg Hillcats.
Multiple websites (along with this card) do in fact confirm that Jeff played for the Mets & Orioles over a 6 season MLB career. He was a super utility player who did everything but pitch and play centerfield over the course of 218 games. He only played in 45 of those games for the Orioles and wasn't able to do much with his bat; he hit .190 for the Birds.
One other thing I found, his dad was Jim McKnight who pitched for the Cubs in the '60s.