OK, OK, we don't all have the rules memorized word-for-word. Me included. Here is the wording. (I had a little trouble with the PDF, so I just typed it by hand, hopefully without too many tpyoes.) The official scorer shall credit an assist to each fielder who throws or deflects a batted or thrown ball in such a way that a putout results, or would have resulted except for a subsequent error by any fielder. Only one assist and no more shall be credited to each fielder who throws or deflects the ball in a run-down play that results in a putout, or would have resulted in a putout, except for a subsequent error; ... So, I would have guessed wrong. I'd have said that only one assist would be credited no matter how long the run-down. Aside from putouts and assists, the official scorecard will show the exact sequence of throws, e.g. 9-3-4-1-3-1-4-2, or whatever. There's more, so have a look if you want more of this good stuff. http://mlb.mlb.com/mlb/downloads/y2015/official_baseball_rules.pdf