I'm breaking mine down into categories. For worst non-playing Mariners Wolry Wolfe and Dez Giraldi are honourable mentions, but I'll go with Andrea Merenda, just because I remember watching him walk through a youth team game with his hands on his knees. For worst imports, Faty, Tavares, Mane, Vernes, Asdrubal, Kim, and Seip would be my shortlist. It's hard to pick from that lot, but I'll give it to Faty for the sheer ineptitude of his debut. There are plenty of contenders for most frustratingly poor - Baird, Pellegrino, Heffernan, Brent Griffiths, Stella, Trott, Van Stratten - but Baird wins it for me. My overall award for a player who was out of his depth and never should have been near the first team of a professional club goes to Tom Slater.
I did have a soft spot for some of the failures though. Tomasevic, Rizzo, McClenahan, Huke, and Sutton spring to mind as players I quite liked, despite their various limitations. Jamie McMaster and Greg Owens too, though they were better than the others. I remember being absolutely convinced that Sutton would be a superb striker for us, he just needed more time. It's probably a good thing I wasn't on here to voice that opinion then. John Sutton wasn't the best hill to die on.