I'd say Dave Littlefield, the Bucs GM did a hell of a job this offseason with the signings and trades.
As of right now the new guys stats....
Sanders: 8 Hits in 12 AB. 4 R, 4 HR, 11 RBI's
Lofton: 3 for 10, 3 R, 1 HR, 3 RBI's.
Simon: 4 for 9, 4 R, 1 HR, 5 RBI's, 2 Doubles.
Stairs: 2 for 4, 1 R.
This is not mentioning all the pitchers he signed too.