Mark Belanger had a couple of pretty weak hitting seasons (although his 1969 season makes him look like a HOFer) and was consistently bad with the bat over a much longer period than Oyler:
http://www.baseball-reference.com/pl...elanma01.shtml
And lest we forget, they named the Mendoza line after this guy for a reason:
http://www.baseball-reference.com/pl...endoma01.shtml