Despite constant speculation from the MGoBoard experts, there actually is no Spinner. According to GERG, there is no fancy name for the position.
"There’s not much hybrid about the linebacker-safety position Stevie Brown will play this year. Robinson said he doesn’t call the position “spinner” or anything else. “He’s our SAM,” or strong-side linebacker, Robinson said."
Can't say that I'm disappointed, Spinner doesn't sound like a football term anyway.
Full article with some notes on the DEATHBACKER! (or Quick) position.