The key to signing Robaire Smith was first coming to terms with free-agent(at the time) Gary Walker. If negoiations would have dragged we might have lost not only Walker but Smith as well. So to me Gary Walker was the key off season move.
If you mean new to the Texans then I could agree, however I think that Todd Wade was the biggest pick-up of the newest Texans, because he allows the offensive line to solidify, tackles & guards no longer out of position.
This will greatly benefit the BIG 3
Carr, Johnson & Davis (statistics & health) which should along with a much improved defense thanks to Gary, Robaire & Seth up front translate into 3-4 more wins in 04.