Scotty,
The stats are cumulative. Each player listed on a roster spot (ie. NOT Bench), accumulates points in that category (1 point per reb,ast,stl etc). It has nothing to do with 2 players going head to head on court.
Lets simplify, using only 1 player per week in our matchup.
Lets say Dirk gets 30 pts, 10 rebs, 5ast, 3 stl, 2 blk, 5 T/O, 2F for the week for you
Lewis gets 25pts, 12 reb, 3ast, 2stl, 2blk, 1T/O, 4F for me.
You'd win Pts, Ast, Stl & F
I'd win Reb & T/o
Blk was a tie, so half a point each.
You'd win the matchup 4.5 to 2.5 (or in Yahoo H2H terms 4-1-2)
Understand?