Thank you Joshua (Sportzcommish)
A very good thought. Doug McWilliams sold or donated at lot of his sports photos to the Baseball Hall.
He did take the photo/postcard below
https://www.tcdb.com/ViewCard.cfm/sid/87098/cid/6286097/1978-Doug-McWilliams-Postcards-78-98-Rene-Lachemann
of Lachemann, but it seems the picture was taken in 1978
Lachemann was connected with Oakland in 1977
https://www.baseball-reference.com/bullpen/Rene_Lachemann.
https://sabrbaseballcards.blog/2016/12/23/doug-mcwilliams-baseball-card-photographer-chronicler-of-baseball-history/
He did take some Mariners so it is possible.
Interesting his collection skips Medich
https://collection.baseballhall.org/PASTIME/doug-mcwilliams-photographic-materials?page=6
I even checked gettyimages. A few leads, but this will be a tough mystery to crack.
thank you
Louis