First and foremost, he was an incredibly important bullpen cog during the Yankees title runs from 1996-2000. As we've seen by the free agent market the past few years, good relievers are tough to come by and are getting paid handsomely. Nelson was as solid as they came, and created an incredible set-up tandem with lefty Mike Stanton that served as the bridge to Mariano Rivera.
Second, he came to the Yankees in the Tino Martinez trade, so he'll always have that connection to my favorite player. I'm not quite sure why the Mariners threw in not one but TWO relievers (Jim Mecir being the other) in addition to Tino for Russ Davis and Sterling Hitchcock. Perhaps the prospects were so highly rated that they needed to? Or the M's needed to cut payroll that much? Nelson was just coming off of a season for the M's in which he went 7-3 with a 2.17 ERA in 78 innings. That's valuable!
He was an emotional leader out there, and it's easy to remember his sidearm motion then striking out a guy and doing a fist pump heading into the dugout. He also loved the 'ol fake-to-third-throw-to-first move. It even worked once!
In 2007, Nelson signed a one-day contract with the Yankees and retired as a member of the organization.
I saw him on the subway platform once but didn't speak to him, as I was in the train and I saw him when the doors opened. The card featured at the top of this post is my first and only autograph of Nellie. He has a cool autograph that I hope he signs sidearm!