The Standard Catalog just lists 1152 as "unidentified player". I will now make it my missing to track down who this is....sort of like how I'm trying to figure out who is on Matt Williams' 1987 Phoenix Firebirds card.
Maybe watch for 1987 timbers stuff on ebay. Might never come up, but I resorted to identifying a background player on one of my cards through a roster included in an autographed ball I spotted there. Like this guy, the background player had his uniform number visible.
It would be easy if only American card manufactures gave a flip about uniform numbers like companies in every other country. As it is, I'll probably have to track down a game program from a Timbers game. There is a Peoria Chiefs program on eBay right now, from a game against the Timbers. I'm just not sure it's worth $10.50 to me to figure this out just yet.
I was wondering the same thing about the unknown guy a couple years back. I think it may be a player named William Diaz who played for them in '86. I found an '86 Wausau card and a couple later cards of him on ebay and the picture looks about the same, although he had a different number in '86. I thought maybe he was intiially on the team in '87 but got moved up before he played a game. Do a search on that name on ebay and take a look at the images.
I don't think it's Diaz. Even accounting for the different angles of his head in the photos, the nose is different. Also, Diaz had that massive Jheri curl on his 1986 card and still later on his 1988 cards.